| In this report , we show that the A Raf kinase is associated with activated EGF receptor complexes and with PDGF receptor ( PDGFR ) complexes independent of prior PDGF treatment . ^^^ Expression of a partially activated A Raf mutant resulted in decreased tyrosine phosphorylation of the PDGFR , specifically on Y 857 ( autophosphorylation site ) and Y 1021 ( phospholipase Cgamma 1 ( PLCgamma 1 ) binding site ) , but not the binding sites for other signalling proteins ( Nck , phosphatidylinositol 3 ' kinase ( PI3K ) , RasGAP , Grb 2 , SHP ) . ^^^ Thus , A Raf can regulate PLCgamma 1 signalling via a PDGFR dependent mechanism and may also regulate PI3K signalling via a PDGFR independent mechanism . . ^^^ |