... involvement of src and PDGFR in tyrosine phosphorylation of S6K further, we studiedthe effect of inhibitors on tyrosine phosphorylation of S6Ks. As expected, genistein, a broad-range tyrosinekinase inhibitor, ... showed an inhibi-tory effect on the phosphotyrosine signal in S6K(Fig. 4B). Interestingly, LY294002 and rapamycin,inhibitors of PI3Kand mTor, respectively, while beingeffective in inhibiting S6K ... compilation ª 2006 FEBS 2023Ribosomal protein S6 kinase (S6K) is a serine ⁄ threon-ine kinase belonging to the family of AGC kinases,which includes protein kinase A (PKA), protein kinaseB...