Analysis of cell cycle proteins as potential p38 downstream targets. (A) Serum-starved NIH3T3 cells were stimulated with FCS or (B) stimulated with FCS in the absence or presence of SB203580 for the indicated time points. Western blot analysis was performed using a phospho-specific (S807/S811) anti-pRB-antibody. The blots were stripped and reprobed with anti-gelsolin-antibody to control equal loading. The same samples were loaded and subjected to Western blot analysis using a pRB-antibody. RB* = phosphorylated pRB. (C) Serum-starved NIH3T3 cells were not pretreated or pretreated with SB203580 and then stimulated with FCS for the indicated time points. Western blot analysis was performed using anti-cyclin D1- (left) or anti-cyclin A-antibodies (right). (D) Serum-starved NIH3T3 cells were exposed to anisomycin or sorbitol for the indicated time points (left) or exposed to sorbitol for 6 h after preincubation with SB203580 (right). Western blot analysis was performed using anti-cyclin D1-antibody. Equal loading was controlled by stripping and reprobing the blots with anti-ERK2-antibody.