Fig. 5. Effect of PD98,059 on the stretch-induced attenuation of mRNA expression of C/EBP and PPAR. 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 3 hours and 45 hours with or without cyclic stretching. The total RNA of 3T3-L1 cells at different times during the respective induction periods was subjected to quantitative RT-PCR and blots of the PCR products were hybridized with DIG-labelled cDNA probes corresponding to each target mRNA. (A) Representative results of the hybridization experiment for quantitatively amplified PCR products. The results of C/EBP at 3 hours as well as PPAR₂ and PPAR₁ at 45 hours after the onset of the induction period are shown. (B-D) Summarized results of the quantitative RT-PCR analysis of the effect of PD98,059 on the expression of C/EBP (B), PPAR₂ (C) and PPAR₁ (D). 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) at 3 hours or 45 hours of induction (n=4 each). Abbreviations: Pre, before induction; Vehi, 0.01% DMSO; PD, 20 µM PD98,059. ^*P<0.05; ^**P<0.01.