FIGURE 8.

PKG II and FAK are both required for FSS-induced gene expression and osteoblast proliferation. A and B, MC3T3 cells were transfected with siRNAs targeting GFP, PKG II, or FAK, and 48 h later they were either kept static (black bars) or exposed to FSS for 1 h (gray bars). Expression of cox-2 (A) or c-fos (B) mRNA was quantified by real-time RT-PCR and normalized to glycerol 3-phosphate dehydrogenase mRNA as described under “Experimental Procedures”; relative cox-2 or c-fos mRNA levels measured in static, GFP siRNA-transfected cells were assigned a value of 1. C, MC3T3 cells were transfected as in A and B and exposed to FSS for 10 min prior to receiving BrdU for 18 h. BrdU incorporation into DNA was detected by immunofluorescence, with >300 cells analyzed/condition. A–C, ***, p < 0.001 for the comparison between static and shear-stressed cells. ###, p < 0.001; ##, p < 0.01 for the comparison with shear-stressed cells transfected with GFP siRNA. ¶, p < 0.05. ns, non-significant.