Fig. 6. PDGF induces the recruitment of p38 MAPK in the plasma membrane compartment and the association of Hsp27-P with cortical cytoskeleton. Quiescent SMC were pre-incubated with 25 µM SB203580 or vehicle for 30 minutes and incubated in the presence or absence of PDGF (10 ng/ml) for 15 minutes. Particulate membrane fractions were extracted with 0.04% Triton X-100. Equal volumes of Triton-soluble membrane fraction (40 µg) and Triton-insoluble membrane fraction were analyzed by immunoblotting using antibodies directed against Hsp27, Hsp27-P, p38 MAPK, a component of the Arp 2/3 complex, p34 Arc, and paxillin. These results are representative of two independent experiments.