CDK1 binds to ∆Np63α and phosphorylates it at T123. (A) HEK293 cells transfected with Flag-∆Np63α were lysed and subjected to immunoprecipitation (IP) with anti-Flag or IgG control. The cell lysate (input) or IP products were subjected to immunoblot (IB) analysis to detect indicated proteins. (B,C) UM1 cells were lysed and subjected to IP with anti-∆Np63α or anti-CDK1, using homologous IgG as controls. The cell lysate (input) or IP products were subjected to immunoblot (IB) analysis to detect indicated proteins. (D) HEK293 cells transfected with Flag-∆Np63α or its T123A mutant, plus CDK1, were lysed and subjected to IP with anti-Flag or IgG control. The cell lysate (input) or IP products were subjected to IB analysis to detect indicated antigens. P-Thr, phosphorylated threonine. (E) UM1 cells were infected with lentivirus-based shRNA specific to CDK1 (shCDK1#1, using shGFP as a control) and selected with puromycin. The resultant stable cell lines were lysed and subjected to IP with anti-∆Np63α. Then the cell lysate (input) or IP products were subjected to immunoblot (IB) analysis to detect indicated antigens.