Phosphorylation of p190 on Tyr1105 by c-Src is necessary but not sufficient for EGF-induced actin disassembly in C3H10T1/2 fibroblasts

p190 RhoGAP is a tyrosine phosphorylated protein that contains an N-termina l GTP binding domain, a middle domain (MD) that mediates interaction with p 120 RasGAP and a C-terminal GTPase-activating protein (GAP) domain that is specific for the Rho family of small GTPases. Evidence is accumulating to s uggest that p190 participates in actin cytoskeleton rearrangements that occ ur following transformation by v-Src or stimulation by growth factors, and that tyrosine phosphorylation of p190 by Src influences these processes. Th e current study was performed to establish whether p190RhoGAP directly part icipates in epidermal growth factor-induced actin stress fiber disassembly and how c-Src is involved in this process, Our results support a model in w hich the p190 MD negatively regulates the activity of the GAP domain and th at c-Src phosphorylation of Y1105 is necessary, but insufficient on its own , for actin stress fiber disassembly.