2-DIMENSIONAL GEL MAPPING OF SMALL GTPASES REVEALS TRANSFORMATION-SPECIFIC CHANGES DURING ONCOGENESIS

Epithelial cells transformed by oncogenes in vitro change their gene e xpression program, thereby losing features of cell polarity and cell a dhesion. Using ras-transformed mammary epithelial cells, we have inves tigated the expression of other small GTP-binding proteins by high-res olution two-dimensional gel electrophoresis and direct GTP ligand bind ing after renaturing transfer onto nitrocellulose. Ras-transformed cel ls lost the expression of one epithelial-specific GTP-binding protein (21-22 kDa, pI 4.5-4.8) and instead expressed a fibroblast GTP-binding protein (21-22 kDa, pI 4.8-5.0)