This application is for partial support of the research in four laboratories in the M.I.T. Cancer Center. The central focus of all the projects is to apply the methods of cell and molecular biology to questions concerning the structure, function, subcellular localization and interactions of proteins important for the behavior of normal and malignant cells. 1. The expression and function of different alternatively spliced forms of fibronectin and of fibronectin receptors will be investigated. The control of the splicing process and the functions of variable segments of fibronectin and of the different subunits of the receptors will be analyzed. 2. Structure-function relationships of NaKATPase subunits and isoforms will be studied. The nature of ouabain resistance will be investigated using gene transfer techniques, site-specific mutagenesis and mutant selection. 3. Functions involved in the intracellular processing of glycoproteins will be analyzed, specifically functions of the endoplasmic reticulum and Golgi apparatus and targeting elements in the glycoproteins will be studied. The effects of various manipulations on glycoprotein processing will be investigated. 4. The structure, variation and functions of chartins, a class of microtubule associated proteins will be investigated. cDNAs for these proteins will be cloned and used to study the properties of this protein family. The basis for the assembly of ordered microtubule arrays will be analyzed in the marginal band of erythrocytes. In these studies, specific probes; recombinant DNA; antibodies; synthetic peptides; etc. will be employed as will be the methods of genetic engineering.