FIGURE 5.

Inhibition of EGFR or MEK1/2 attenuates mechanical stress-induced CHI3L1 expression. A, ERK phosphorylation response to mechanical stress was measured by Western blot analysis. B, ERK phosphorylation in the presence or absence of AG1478 (500 nm) and U0126 (10 μm) was measured by Western blotting and quantified by densitometry analysis. E-cadherin was used as a loading control. C, CHI3L1 expression in the presence or absence of AG1478 (500 nm) and U0126 (10 μm) was measured by a real-time PCR. Data are represented as the mean ± S.D. from independent experiments (n = 4) (*, p < 0.005 vehicle (Veh) + pressure versus control; †, p < 0.005 AG1478 + pressure versus vehicle + pressure; ††, p < 0.05 U0126 + pressure versus vehicle + pressure). D, CHI3L1 expression in the presence or absence of AG1478 (500 nm) alone or in combination with each inhibitor (NSC23766 (NSC, 100 μm), C3 transferase (C3, 2 μg/ml), Y27632 (10 μm), or FAK inhibitor-14 (FAK I-14, 50 μm)) was measured by real-time PCR. Data are represented as the mean ± S.E. from independent experiments (n = 3) (*, p < 0.005 vehicle + pressure versus control; †, p < 0.05 versus vehicle + pressure).