Figure 9.

Effect of Inhibition of PDGFR Downstream Kinases on PLK4 Phosphorylation

(A) P38 inhibition mitigates PLK4 phosphorylation. Rat primary adventitial fibroblasts were cultured, starved, and pretreated with vehicle (DMSO) or a kinase inhibitor (5 μmol/l, 30 min), and then stimulated with AA (60 ng/ml) for 10 min before harvest for Western blotting. The arrow points to the bands of phospho-PLK4. Inhibitors: JNK (SP600125), PI3K (LY294002), mTOR (rapamycin). P38 (SB230580), and MEK/ERK (PD98059). (B) P38 silencing mitigates PLK4 phosphorylation. Rat primary adventitial fibroblasts were transfected with scrambled (Scr) or P38-specific siRNA (siP38), cultured, starved, and then stimulated with AA (60 ng/ml) for 10 min before harvest for Western blotting. (C) Effect of P38 inhibition on PLK1 phosphorylation. Experiments were performed as described in (A) except for detection of p-PLK1 (T210). Quantification: mean ± SEM, n ≥3 experiments, 1-way ANOVA/Bonferroni test: #p < 0.05; ##p < 0.01; ###p < 0.001. ∗p < 0.05; ∗∗p < 0.01; ∗∗∗p < 0.001 compared with the vehicle control (with AA, the white bar in A and C) or the scrambled siRNA control without AA (the first bar of plot in B). Abbreviations as in Figures 1 and 4.