Figure 4.

Downregulation of CD44 attenuates EGF-mediated activation of EGFR signaling, potentially through enhanced EGFR degradation. (A) Cells were seeded into 6-well plate at 1.5×10⁵ cells/well and transfected with sictr or siCD44 for 24 h. After stimulation by EGF (50 ng/ml) for 0, 5, 10, 20 and 60 min, total protein were collected for western blotting. The protein expression of EGFR, p-EGFR Tyr1068, p-EGFR Tyr1173, SRC, p-SRC Tyr416, AKT, p-AKT Ser473, ERK and p-ERK Tyr204 were assessed. Accordingly, the relative expressions of (B) p-EGFR Tyr1068, (C) p-EGFR Tyr1173, (D) p-SRC Tyr416, (E) p-AKT Ser473, and (F) p-ERK Tyr204 to GAPDH were calculated by ImageJ. Data were presented as mean ± SD of 3 independent experiments. ^*P<0.05 vs. sictr. sictr, control siRNA; siCD44, CD44 siRNA; p, phosphorylated; EGFR, epidermal growth factor receptor.