Fig. 4. Western-blot analysis of the activation of the ERK/MAPK pathway. (A) Representative western-blot analyses using anti-ERK and anti-phosphorylated-ERK antibodies. (B,C) Summarized results of the densitometric analyses of total ERKs (B) and phosphorylated ERKs (C) (n=3 each). (D) Summarized results of the effect of PD98,059 on the activation of ERKs (n=8-10 each). The 3T3-L1 cells were incubated in induction medium (DEX/MIX/INS) containing either 20 µM PD98,059 (designated PD) or 0.01% DMSO (Vehi) for 45 hours with or without cyclic stretching. The white bar represents the cells before induction (Pre), the black bar represents the cells without stretching (Rest) and the grey bar represents the cells with cyclic stretching (Stretch; at 130%, 1 Hz) during the induction period. ^*P<0.05; ^**P<0.01.