FIGURE 3.

FSS-induced Akt activation requires both Src and FAK, whereas cGMP-induced Akt activation is FAK-independent. MC3T3 cells were transfected with siRNAs targeting GFP (control), FAK, or Src, as described under “Experimental Procedures.” After 48 h, cells were exposed for 5 min to either FSS (A), or 50 μm 8-pCPT-cGMP (B), and Akt phosphorylation was determined as in Fig. 1A. Western blots showing expression of FAK and Src are shown in the bottom two panels of A. C, the graph summarizes three independent experiments for each treatment, with the relative amount of pAkt found in FSS- or cGMP-treated cells transfected with GFP siRNA assigned a value of 1 (**, p < 0.01 for the comparison between FAK and GFP siRNA-transfected cells; ***, p < 0.001 for the comparison between Src and GFP siRNA-transfected cells). Error bars, S.E.