CDK1 and urinary bladder cancer: By analyzing the transcription targets and interacting proteins of Tfcp2l1, a pluripotency‐associated transcription factor of murine embryonic stem cells (ESCs), and performing multiplex immunostaining of bladder cancer specimens from 400 patients, we demonstrate that Thr177 phosphorylation of TFCP2L1 by CDK1 is critical for embryonic stem cell (ESC) pluripotency in embryos as well as bladder carcinogenesis in adults.