Our previous studies indicated that the expression of caveolin-1 is suppressed and molecular reaction with caveolin-2 is aberrantly disturbed upon transformation with oncogenic S-ras(Q61K). In the present study, we attempted to investigate the reaction of caveolins in cells transfected with embryonic ras, E-ras. The expression of caveolin-1 and caveolin-2 were less suppressed in E-ras transfected cells as compared to cells transfected with S-ras(Q61K). When cellular plasma membranes were isolated and subjected to fractionation with phase-separating agent, Triton X-114, caveolin-2 was totally retained in hydrophobic phase from cells with transfection or not. Similarly, most of caveolin-1 was retained as caveolin-2 except caveolin-1b. An additional fraction of caveolin-1b was found in peripheral membrane fraction of E-ras transfected cells. This extraordinary presence of caveolin-1b and suppressed expression of caveolin-1 resulted in depleted cholesterol recruitment at caveolae. As shown by ultracentrifugation with sucrose gradients, most of caveolae from E-ras transfected cells appeared in 39-43% of sucrose in contrast with 31-35% of sucrose in BALB/3T3 cells without transfections. The reactivity of kinase molecules at caveolae upon depletion of caveolin-1b was investigated in E-ras transfected cells and embryo.