the invention will now be described in more detail with reference to the following figures and examples in which : fig1 shows the effects of synthetic peptides and fibronectin domains on cell migration in the native collagen gel assay . assays were performed as described in materials and methods in example 1 . results are normalised by expressing them as “ relative stimulation ” of migration , this being calculated by dividing the percentage of cells in the gel matrix for each experimental point by the control value obtained in that particular experiment . data are presented as the mean ± sd of five experiments . for clarity , the shaded area indicates the spread of standard deviations for data points not plotted with error bars . upper panel : results obtained with the indicated synthetic peptides . lower panel : results obtained with native fibronectin ( fn ), and its cell - binding ( cell - bd ) and gelatin - binding ( gel - bd ) domains . fig2 shows the effects of synthetic peptides and fibronectin domains on cell migration in the transmembrane assay . assays were performed as described in materials and methods in example 1 . results from five experiments are presented as mean ± sd . shaded area indicates the spread of standard deviations for data points not plotted with error bars . panel a : results obtained with igds ( seq id no 2 ) and the gelatin - binding domain ( gel - bd ) on membranes coated with native collagen and gelatin . panel b : results obtained with rgds ( seq id no 6 ), native fibronectin ( fn ), and its cell - binding domain ( cell - bd ). fig3 shows the effect of different peptides on the migration of stimulating activity of the gelatin - binding domain of fibronectin and igds ( seq id no 2 ). the collagen gel assay was performed in the presence of various combinations of the indicated peptides and the percentage of cells present within the gel matrix measured after a four - day incubation period . data are expressed as mean ± sd obtained in three experiments . panel a : combinations of the gelatin - binding domain ( gel - bd ) and igds ( seq id no 2 ); panel b : combinations of igds ( seq id no 2 ) and rgds ( seq id no 6 ); panel c : combinations of igds ( seq id no 2 ) and the cell - binding domain ( cell - bd ). fig4 shows the effect of pre - incubation of cells with synthetic peptides on their subsequent migration in the native collagen gel assay . confluent cells on plastic tissue culture dishes were washed 3 × with serum - free mem ( sf - mem ) and then incubated for various times with the indicated concentrations of igds ( seq id no 2 ) in sf - mem . they were then trypsinised and washed extensively by repeated ( 5 ×) cycles of centrifugation and resuspension in sf - mem . the behaviour of these pre - incubated cells was assessed in the collagen gel assay in the absence of further igds ( seq id no 2 )( indicated as igds ( seq id no 2 ) not in assay ). these results were compared with the response of control cells to igds ( seq id no 2 ) present during the four - day duration of the migration assay ( indicated as igds ( seq id no 2 ) in assay ). data were obtained from three experiments and are expressed as mean ± sd . fig5 shows the primary amino acid structure of human fibronectin . type i repeats : 52 – 96 , 97 – 140 , 141 – 185 , 186 – 230 , 231 – 272 , 308 – 344 , 470 – 517 , 518 – 560 , 561 – 608 , 2297 – 2341 , 2342 – 2385 , 2386 – 2428 type iii repeats : 609 – 700 , 719 – 809 , 810 – 905 , 906 – 995 , 996 – 1085 , 1086 – 1172 , 1173 – 1265 , 1357 – 1447 , 1448 – 1537 , 1538 – 1631 , 1632 – 1721 , 1812 – 1903 -, 1904 – 1992 , 1993 – 2082 , 2203 – 2273 potential n - linked glycosylation sites : 430 , 528 , 542 , 877 , 1007 , 1244 , 1291 , 15 1904 , 2199 fig6 shows the modulation of the effect of gbd and the igds ( seq id no 2 ) tetrapeptide on fibroblast migration into 3d collagen matrices by cell density . cells were plated at either confluent ( conf ) or subconfluent ( subconf ) densities . shaded area indicates range of control values . fig7 shows the angiogenic activity of igds ( seq id no 2 ) synthetic peptide and gelatin - binding domain of fibronectin in the chick yolk sac membrane assay . dried methylcellulose pellets containing the test samples and control pellets ( lacking the test samples ) were placed on the yolk sac membrane of 6 - day chick embryos , as described in materials and methods in example 1 . the elicited reaction was checked after six hours and assessed after 24 hr by observation of living embryos with a stereomicroscope . a . negative angiogenic response ( in this case , elicited by control pellet ); b . typical positive angiogenic response ( in this case , elicited by pellet containing 1 . 0 μg igds ( sew id no 2 )). after assessment at 24 hr , selected membranes were fixed in 2 . 5 % em grade glutaraldehyde in 0 . 2 m phosphate buffer , ph 7 . 4 . these preparations were then stained with 1 % toluidine blue and photographed using a leica dm lb microscope . c . appearance of fixed and stained positive angiogenic response ( in this case , elicited by pellet containing 1 . 0 μg of the gelatin - binding domain ). bar = 250 μm . migration stimulating activity of the igd ( seq id no 1 ) amino acid motif the gelatin - binding domain of fibronectin stimulates fibroblast migration into matrices of native type i collagen , but is devoid of such activity with cells adherent to a denatured collagen substratum . we now demonstrate the igd ( seq id no 1 ) motif , present at two sites within the gelatin - binding domain , displays the same substratum - dependent activity . micromolar concentrations of idg - containing synthetic peptides stimulated fibroblast migration into native ( but not denatured ) collagen substrata in the following activity order : igds ( seq id no 2 )& gt ; igdq ( seq id no 3 )& gt ; igd ( seq id no 1 ). the related rgds ( seq id no 6 ) peptide did not affect cell migration on its own and inhibited the bioactivity of igds ( seq id no 2 ) in a dose - dependent fashion . cells pre - incubated with igds ( seq id no 2 ) displayed a persistent stimulation of cell migration when assayed in the absence of further igds . this feature of igds ( seq id no 2 ) bioactivity provided a means to study the early events of igds ( seq id no 2 ) action ( for example , receptor ligation and post - ligation signalling ) separately from the late events resulting in the persistent stimulation of cell migration . accordingly , experiments in which cells were incubated with igds ( seq id no 2 ) and inhibitors in various temporal combinations indicated that ( a ) both early and late events of igds ( seq id no 2 ) action were effectively inhibited by rgds , as well as function - blocking antibodies to integrin subunits ( β 1 and β 3 ) and heterodimer α v β 3 , ( b ) neutralising antibodies to the classic fibronectin - binding α 5 β 1 , integrin were without effect , and ( c ) inhibition of tyrosine kinase activity blocked early events of igds ( seq id no 2 ) action , inhibition of map kinase kinase blocked both early and late events , whilst inhibition of pka only affected late events . in vivo studies further indicated that igds ( seq id no 2 ) synthetic peptide elicited an angiogenic response in the chick yolk sac membrane ; in contrast , rgds ( seq id no 6 ) and rges ( seq id no 11 ) peptides were inactive under the same experimental conditions . the expression of biological activity by idg ( seq id no 1 ) synthetic peptides ( both in vitro and in vivo ) stands in marked contrast to the inactivity of their well - studied rgds ( seq id no 6 ) counterparts and opens the possibility of developing a novel family of clinically relevant agents . chemicals . the synthetic peptides were prepared to greater than 99 % purity in the department of biochemistry , university of dundee . fibronectin and its cell - binding and gelatin - binding domains were purified as previously described 7 . monoclonal antibodies to the integrin subunits α2 ( cat . no . mca743 ) and β1 ( mca1188 ) were supplied by serotec ( oxford , uk ); antibodies to β3 ( mab1957 ), αvβ3 ( mab1976 ) and α5β1 ( mab 1969 ) were supplied by chemicon ( harrow , uk ); antibody to α5β1 ( m0604 ) was supplied by dako ( high wycombe , uk ). genistein ( cat . no . 34583 - q ) and pd98059 ( cat . no . 178278 - q ) were purchased from calbiochem , nottingham . pka inhibitor peptide ( cat . no . p6062 ) was purchased from sigma chemical co ( poole , dorset , uk ). cells . experiments were performed with two lines of human skin fibroblasts ( sk319 and fsf44 , between passage 10 – 18 ) shown to be free of mycoplasmal contamination by staining with hoechst 33256 . identical results were obtained with both lines and these cells are consequently not individually identified in the figures . stock cultures were maintained in eagle &# 39 ; s minimal essential ( mem ), as previously described 7 . migration assays . in the collagen gel assay , pre - formed 2 ml gels were overlaid with 1 ml of serum - free mem ( controls ) or serum - free mem containing the requisite concentration of effector molecule to give the desired final concentration . trypsinised fibroblasts were suspended in serum - free mem to give an inoculum containing 2 × 10 5 cells / ml and 1 ml of this was plated onto replicate control and test gels . after a 4 - day incubation period at 37 ° c ., the cells on the surface and within the 3d matrix of the gel were counted in 15 randomly selected fields by microscopic observation and these data used to calculate the percentage of total cells present within the gel matrix 6 . polycarbonate membranes used in the transmembrane assay were immersed in an aqueous solution containing 10 μg / ml of either native type i collagen or heat - denatured type i collagen ( gelatin ) overnight at 37 ° c . and then air - dried . assays were performed as previously described 7 . chick yolk sac membrane angiogenesis assay . the assay was performed essentially as described by gush et al ( 1990 ) j . med . engineer . tech . 14 , 205 – 209 . accordingly , four - day - old fertilised eggs were cracked in a tumbler , covered with a petri dish and incubated at 37 ° c . two days later dried methylcellulose pellets containing the test samples and control pellets ( lacking the test samples ) were placed on the yolk sac membrane . the elicited angiogenic reaction was assessed after 24 hr by observation of living embryos with a stereomicroscope . selected membranes were fixed in 2 . 5 % em grade glutaraldehyde in 0 . 2 m phosphate buffer ( ph 7 . 4 ), dissected , stained with 1 % toluidine blue and mounted on glass slides for photomicroscopy . inspection of the amino acid sequence of the gelatin - binding domain revealed that it contains two igd ( seq id no 1 ) motifs located in the seventh and ninth type i repeat modules , respectively . this is of particular interest , as the igd ( seq id no 1 ) motif is a highly conserved feature of the type i module 8 and its location at the apex of the main type i loop is homologous to that of the rgd ( seq id no 4 ) motif in the tenth type iii repeat 9 . relevant igd - containing synthetic peptides were synthesised and their effect on the migration of human dermal fibroblasts examined in the collagen gel assay . results summarised in fig1 a indicate that igds ( seq id no 2 )( as present in the ninth type i module ), igdq ( seq id no 3 )( as present in the seventh type i module ) and igd ( seq id no 1 ) stimulated cell migration into native type i collagen gels in a dose - dependent fashion . significant bioactivity was expressed by igds ( seq id no 2 ) and igdq ( seq id no 3 ) at a concentration of 0 . 1 μm , whilst comparable activity was first manifest by igd ( seq id no 1 ) at 10 – 100 μm . igds ( seq id no 2 ) produced a bell - shaped dose - response ; this was not obtained with either igdq ( seq id no 3 ) or igd ( seq id no 1 ) within the concentration range examined . the structurally related rgds ( seq id no 6 ) tetrapeptide was devoid of migration stimulating activity in the native collagen gel assay . comparative results obtained with purified , proteolytically - generated , fibronectin fragments ( fig1 b ) confirmed our previous observations that the gelatin - binding domain exhibits significant migration stimulating activity , whilst native fibronectin and its purified cell - binding domain are inactive when tested within the same concentration range 7 . comparison of data presented in figs . ia and b further indicate that the micromolar concentration range of igd ( seq id no 1 )- containing synthetic peptides required to induce a stimulation of cell migration is many orders of magnitude greater than the corresponding femtomolar concentration range of the larger gelatin - binding domain . these observations suggest the involvement of other amino acid motifs within the gelatin - binding domain in facilitating recognition and / or binding of igd ( seq id no 1 ) to its putative cell surface receptor . in this context , aota et al 10 reported that the phsrn ( seq id no 12 ) sequence in the ninth type iii module of the cell binding domain is such a “ synergistic ” motif for rgd - dependent biological activity . the effects of a native and denatured type i collagen substratum on the migration stimulating activity of igd - containing synthetic peptides was assessed in the transmembrane assay . data presented in fig2 a indicate that igds ( seq id no 2 ) stimulated cell migration through membranes coated with native collagen , but was devoid of activity on gelatin - coated membranes . similar results were obtained with igdq ( seq id no 3 ) and igd ( seq id no 1 )( data not shown ). these observations indicate that the bioactivity of igd - containing synthetic peptides is ( a ) dependent upon cell attachment to a native collagen substratum , and ( b ) resembles that of the larger gelatin - binding domain in which it is contained in terms of this criterion . the mechanism responsible for the substratum - dependent nature of igd ( seq id no 1 ) activity remains to be determined . in this regard , it may be relevant that cellular adhesion to a native collagen substratum specifically affects a number of cellular processes of potential relevance to the modulation of cell migration ( for example , phosphorylation of pp125fak and activation of pkc - ζ ) 11 , 12 . data presented in fig2 b confirm that native fibronectin and its purified cell binding domain stimulate cell migration through membranes coated with gelatin ( as reported in previous studies ) and that the rgds ( seq id no 6 ) synthetic peptide is inactive on both collagen - and gelatin - coated membranes . the possible mechanistic relationship between igds ( seq id no 2 ) and the gelatin - binding domain in which it is contained was further examined by co - incubating cells with suboptimal concentrations of each . the results presented in fig3 a indicate that these two peptides exerted an additive effect upon cell migration , consistent with the hypothesis that the igd ( seq id no 1 ) motif within the gelatin - binding domain is indeed responsible for its stimulation of cell migration . this additive effect was particularly apparent at 0 . 1 fm gbd and 0 . 01 μm ( 10 7 fm ) igds , which were each inactive when present on their own , but active in combination . possible mechanistic interactions between igds ( seq id no 2 ) and rgds ( seq id no 6 ) were studied in similar co - incubation experiments . results presented in fig3 b indicate that rgds ( seq id no 6 ) effectively inhibited the migration stimulating activity of igds ( seq id no 2 ). the cell - binding domain of fibronectin ( which contains the rgds ( seq id no 6 ) motif also inhibited igds ( seq id no 2 ) activity ( fig3 c ). as expected , the inhibition of igds ( seq id no 2 ) activity was achieved at considerably lower ( nanomolar ) concentrations of the cell - binding domain compared to the pmolar concentrations required of rgds ( seq id no 6 ). the rges ( seq id no 11 ) synthetic peptide had no effect on igds ( seq id no 2 ) migration stimulating activity when tested at the same concentration range as rgds ( seq id no 6 )( data not shown ). a number of biological activities of fibronectin are “ cryptic ” in the sense that they are displayed by fibronectin proteolytic fragments , but not by the intact molecule 5 , 13 . fukai et al 14 have demonstrated that the expression of these cryptic activities require either the denaturation of native fibronectin and / or its limited proteolytic degradation into functional domains in order to become manifest . these authors suggest that relaxation of steric hindrance may be responsible for the unmasking of latent biological activity by these procedures . the inhibition of igds ( seq id no 2 )- induced cell migration by the rgds ( seq id no 6 ) amino acid motif may provide an additional mechanism for the apparent lack of igds ( seq id no 2 ) activity in native fibronectin ( fig1 b ). we have previously reported that cells pre - incubated for 24 hr with the gelatin - binding domain of fibronectin displayed elevated migratory activity when subsequently plated on native collagen gels in its absence 7 . data presented in fig4 indicate that the effect of igds ( seq id no 2 ) on cell migration is similarly persistent , exhibiting a dependence upon both the time of pre - incubation and peptide concentration . this elevated migratory behaviour is still manifest by pre - incubated cells following 1 – 2 passages in vitro ( data not shown ). the persistence of igds ( seq id no 2 )- bioactivity suggests that its mode of action involves a series of early events which are dependent upon the presence of igds ( seq id no 2 )( such as receptor ligation and post - ligation signalling ) and later events , which no longer require the presence of igds ( seq id no 2 ) and ultimately result in stabilisation of a persistent migratory phenotype . the specific effects of potential inhibitory molecules on such early and late events were examined by using the following experimental protocol : ( a ) pre - incubating cells with igds ( seq id no 2 ) and inhibitor and then assaying these treated cells in the absence of both igds ( seq id no 2 ) and inhibitor ( note : this protocol provides data concerning the effects of inhibitor on the early events mediating igds ( seq id no 2 ) activity ), ( b ) pre - incubating cells with neither igds ( seq id no 2 ) nor inhibitor and assaying them in the presence of both ( the effects of inhibitor on both early and late events ), ( c ) pre - incubating cells with igds ( seq id no 2 ) alone and then assaying them in the presence of inhibitor only ( the effects of inhibitor on late events ), and finally , ( d ) pre - incubating cells with inhibitor alone and then assaying them in the presence of igds ( seq id no 2 ) to provide control information regarding possibly persistent effects of inhibitor which would confound data interpretation . data presented in table ia are concerned with the effects of the synthetic rgds ( seq id no 6 ) and rges ( seq id no 5 ). our results indicate that rgds ( seq id no 6 ) inhibited both igds ( seq id no 2 ) cell signalling and subsequent cell migration . rges ( seq id no 11 ) was inactive under all experimental conditions . control data ( protocol “ d ”) indicated that both peptides had no persistent effect on igds ( seq id no 2 ) activity ; all of the other inhibitors examined were similarly devoid of such potentially confounding activity ( data not shown ). the inhibitory effects of rgds ( seq id no 6 ) on igds - induced cell migration may occur by competition for receptor ligation . in order to obtain data relevant to this possibility , we employed the above pre - incubation protocols to examine the effects of neutralising antibodies to several integrins expressed by human dermal fibroblasts in vitro 15 our data indicate that the monoclonal antibody recognising the a2 integrin subunit inhibited cell migration induced by igds ( seq id no 2 ), but did not affect initial igds ( seq id no 2 ) signalling ( table 3b ). this observation is consistent with the role of α2β1 in mediating cell attachment to collagen and its involvement in supporting cell migration on this substratum 16 . antibodies to the αvβ3 heterodimer , as well as to the integrin subunits α1 and β3 , were found to block both the initial events of igds ( seq id no 2 ) signalling and subsequent cell migration . the αvβ3 heterodimer recognises the rgds ( seq id no 6 ) motif , whilst the β 1 and β 3 subunits are present in several integrin heterodimers which also recognise rgds 15 , 17 . several previous studies have implicated these integrins in the mediation of cell migration 16 , 18 . in this context , it should be noted that the α v β 3 heterodimer also binds to exposed rgd ( seq id no 4 ) sites in denatured ( but not native ) collagen 19 ; this differential ligation of denatured and native type i collagen by α v β 3 may contribute to the substratum - dependent nature of fibroblast migratory response to igd - containing peptides reported here . two antibodies to the “ classic ” fibronectin - binding α 5 β 1 integrin had no effect on igds - induced cell migration ( table 3b ). these observations are consistent with previous reports suggesting that integrin α 5 β 1 preferentially mediates cell adhesion rather than migration 20 . recent studies have underscored the interplay between substratum , ligand concentration and integrin function in the control of cell migration 21 , 22 ; these complex factors will need to be taken into account in identifying the precise integrin receptors involved in igd ( seq id no 1 ) ligation and the post - ligation events leading to the resultant substratum - dependent biological activity . results obtained with signal transduction inhibitors indicate that the tyrosine kinase inhibitor genistein selectively blocked igds ( seq id no 2 )- induced cell signalling , but did not affect cell migration ( table 1c ). this finding is consistent with the role of focal adhesion - associated tyrosine kinases ( such as pp125fak ) in mediating integrin signal transduction 23 . the map kinase kinase inhibitor pd98059 blocked both signal transduction and cell migration , in keeping with the previously reported activation of the map kinase cascade by integrin ligation 24 . in contrast , the pka inhibitor blocked cell migration , but did not appear to affect initial igds ( seq id no 2 )- dependent events . in addition to rgd , other amino acid sequences in fibronectin have been reported to mediate cell adhesion and migration ; these include ldv ( seq id no 9 ), redv ( seq id no 9 ) and idaps ( seq id no 8 ) 17 . all these motifs resemble rgd ( seq id no 4 ) in that migration stimulating activity is not retained by the respective soluble synthetic peptides . the migration - stimulating activity of igd - containing synthetic peptides appears to be unique in this sense . although biological activity has not previously been ascribed to the conserved igd ( seq id no 1 ) motif in fibronectin , previous studies have implicated the ninth type i repeat ( which contains the igds ( seq id no 2 ) sequence in the assembly of an extracellular fibronectin matrix 25 . the data presented here may be relevant in this context and suggest several integrins which may function in igds ( seq id no 2 ) ligation . the migration inhibiting activity of rgd - containing peptides has a number of potential clinical applications 26 , 27 . structure - function studies have indicated that conservative and non - conservative amino acid substitutions , tandem amino acid extensions and cyclicisation significantly modulate the biological activity of the rgd ( seq id no 4 ) motif in these situations 28 , 29 . the converse migration - stimulating activity of igd ( seq id no 1 )- containing synthetic peptides may provide an analogous platform for developing a new family of therapeutic agents which promote cell migration in clinically relevant conditions , such as impaired wound healing . the igds ( seq id no 2 ) peptide has been shown to stimulate fibroblast migration and elicit and angiogenic response in a rat wound healing model . in this experimental system , 1 cm 2 pieces of porcine dermal collagen films impregnated with either control medium or medium containing the indicated concentration of test substance were implanted subcutaneously into rats . the animals were sacrificed 28 days later and the removed collagen implants fixed and sectioned for image analysis . the following data were obtained , indicating that igds ( seq id no 2 ) stimulated both fibroblast migration into the collagen film and an angiogenic response . 1 . zardi , l . et al ( 1985 ) eur . j . biochem . 146 , 571 – 579 . 2 . postlethwaite , a . e . et al ( 1981 ) j . exp . med . 153 , 494 – 499 . 3 . albini , a . et al ( 1987 ) j . cell . biol . 105 , 1867 – 1872 . 4 . akiyama , s . k . & amp ; yamada , k . m . ( 1985 ) j . biol . chem . 260 , 10402 – 10405 . 5 . clark , r . a . f . et al ( 1988 ) j . biol . chem . 263 , 12115 – 12123 . 6 . schor , s . l . ( 1980 ) j . cell sci . 41 , 159 – 175 . 7 . schor , s . l . et al ( 1996 ) j . cell sci . 109 , 2581 – 2590 . 8 . hynes , r . o . ( 1990 ) fibronectins pp 132 – 135 , springer - verlag : new york . 9 . main , a . l . et al ( 1992 ) cell . 71 , 671 – 678 . 10 . aota , s . et al ( 1994 ) j . biol . chem . 269 , 24756 – 24761 . 11 . roekel , d . & amp ; krieg , t . ( 1994 ) exp . cell res . 211 , 42 – 48 . 12 . xu , j . & amp ; clark , r . a . f . ( 1997 ) j . cell biol . 136 , 473 – 483 . 13 . fukai , f . et al ( 1993 ) biochem . 32 , 5746 – 5751 . 14 . fukai , f . et al ( 1995 ) biochem . 34 , 11453 – 11459 . 15 . gailit , j . & amp ; clark , r . a . f . ( 1996 ) j . cell biol . 106 , 102 – 108 . 16 . yamada , k . m . et al ( 1990 ) cancer res . 50 , 4485 – 4496 . 17 . yamada , k . m . ( 1991 ) j . biol . chem . 266 , 12809 – 12812 . 18 . tooney , p . a . ( 1993 ) immunol . cell biol . 71 , 131 – 139 . 19 . davis , g . e . ( 1992 ) biochem . biophys . res . commun . 182 , 1025 – 1031 . 20 . chan , b . m . et al ( 1992 ) cell . 68 , 1051 – 1060 . 21 . schwartz , m . a . et al ( 1995 ) annu . rev . cell dev . biol . 11 , 549 – 599 . 22 . palecek , s . p . et al ( 1997 ) nature 385 , 537 – 540 . 23 . richardson , a . & amp ; parson , j . t . ( 1995 ) bioessays 17 , 229 – 236 . 24 . chen , q . et al ( 1994 ) j . biol . chem . 269 , 26602 – 26605 . 25 . chernousov , m . a . et al ( 1991 ) j . biol . chem . 266 , 10851 – 10858 . 26 . humphries , m . j . et al ( 1994 ) exp . opin . ther . patents 4 , 227 – 235 . 27 . pierschbacher , m . d . et al ( 1994 ) j . cell biochem . 56 , 150 – 154 . 28 . yamada , k . m . & amp ; kennedy , d . w . ( 1985 ) j . cell biochem . 28 , 99 – 104 . 29 . pierschbacher , m . d . & amp ; ruoslahti , e . ( 1987 ) j . biol . chem . 262 , 17294 – 17298 . 30 . hunt , t . k . wound healing and infection : theory and surgical practice appleton - century - crofts : new york ( 1980 ). 31 . britsch , s ., christ , b . & amp ; jacob , h . j . “ the influence of cell - matrix interactions on the development of quail chorioallantoic vascular system ” anal . embryol . 180 , 479 – 484 .
a compound with a relative molecular mass of less than 15000 comprising the peptide ile - gly - asp or a peptide or non - peptide mimic thereof . the compounds may be used to modulate cell migration and are useful in angiogenesis .