Fig. 4.

TOPK is required for EGF-induced PRPK phosphorylation. (a) EGF induces a time-dependent phosphorylation of PRPK and phosphorylation of PRPK decreases with depletion of TOPK in HCT116 cells. Total TOPK was used as an internal control for confirmation of TOPK deficiency (shTOPK). β-Actin was used to verify equal protein loading. (b and c) TOPK promotes phosphorylation of PRPK in HEK293 cells after treatment with EGF. The same amount of pcDNA3-HA-TOPK and pcDNA-V5-PRPK (b) and increasing amounts of pcDNA3-HA-TOPK (c) were transiently transfected into HEK293 cells and phosphorylation of PRPK was detected by Western blot analysis with specific antibodies after EGF (20 ng/ml) treatment for 30 min.