Fig. 4. ARAP3-deficient cells have increased activities of RhoA. (A) NA1 and 52B3 cells were transiently transfected with a Myc-tagged ROCK construct. After 16 hours of serum starvation, cells were or were not stimulated with PDGF or its vehicle for 1-15 minutes and lysed. ROCK protein was immunoprecipitated using an anti-Myc antibody and subsequently used for an in vitro kinase assay. The graph represents data pooled (means ± s.d.) from three independent experiments, which were all done in duplicate. The PDGF-stimulated increase in ROCK activity in the 52B3 cells is statistically significant (*P=0.05 in a paired Student's t-test). (B) NA1 and 52B3 cells were seeded into tissue culture dishes, serum starved for 16 hours and lysed straight away or after stimulation with PDGF or its vehicle for 1-10 minutes. Lysates were subjected to western blotting and probed with an anti phospho-MYPT antibody and subsequently with a control antibody (ß-COP) as a loading control. The shown blot is a representative example from three independent experiments.