SYNERGISTIC ACTION OF R-RAS AND IGF-1 ON BCL-XL EXPRESSION AND CASPASE-3 INHIBITION IN BAF3 CELLS - R-RAS AND IGF-1 CONTROL DISTINCT ANTI-APOPTOTIC KINASE PATHWAYS

R-Ras and insulin-like growth factor-1 (IGF-1) synergistically inhibit apoptosis of BaF3 cells upon interleukin-3 deprivation. To characteri ze the mechanism of this synergistic inhibition, we examined the effec t of R-Ras and IGF-1 on several apoptosis-related proteins. Extracellu lar signal-regulated kinase (ERK) was activated by IGF-1, but not by R -Ras. In contrast, Akt was activated strongly by R-Ras, but weakly by IGF-1, It was also found that R-Ras and IGF-1 cooperatively induced Bc l-xL expression and inhibited caspase-3 activation. (C) 1998 Federatio n of European Biochemical Societies.