Excised mammary gland tissues from non-treated, lactating and tumors from Xenobiotic (dimethylbenz[a]anthracene and endosulfan) induced female rats will be utilized to conduct isolation and biochemical characterization of putative cell (plasma) membrane associated galactosyltransferase(s) as regulation molecules in cell-cell contact and contact inhibition; the latter suspected of being causal in tumorigenesis. These mammary gland and tumor tissues will be subjected to subcellular fractionation, electron microscopy, affinity chromatography, SDS-PAGE, High Pressure Liquid Chromatography, and Thin-Layer Chromatography for comparative IN SITU enzyme(s) moiety analyses. These studies seek to determine the putative functional role(s) of membrane-associated galactosyltransferase(s) in cell proliferation.