Fig. 4: CDK1 is the upstream kinase of MED15 T603 phosphorylation.

a Immunoblot analysis using the indicated antibodies in HaCaT cells treated without or with kinase inhibitors. b Kinase inhibitors and their target kinases. c The chemical structure of Ro3306. d Immunoblot analysis with the indicated antibodies in HaCaT cells transfected without or with si-CDK1. e Immunoblot analysis with the indicated antibodies in HeLa cells transfected without or with si-CDK1. f Immunoblot analysis with the indicated antibodies in WT and T603A mutant HaCaT cells treated without or with 10 μM Ro3306 and 2 ng/mL TGFβ. g qRT-PCR assays were performed to determine the mRNA levels of CDK1 in HaCaT cells transfected without or with si-CDK1. The values are presented as means ± SD. **P < 0.01. h qRT-PCR assays were used to determine the mRNA levels of SASP genes in HaCaT cells transfected without or with si-CDK1. The values are presented as means ± SD. *P < 0.05 and **P < 0.01. i qRT-PCR assays were used to determine the mRNA levels of p21 in HaCaT cells treated without or with si-CDK1 and TGFβ. The values are presented as means ± SD. *P < 0.05. j Schematic model showing that CDK1 phosphorylates MED15 at T603.