CDK9 and cancer: Atuveciclib inhibits the binding of HIF-1α to MCL-1 promoter and reduces MCL-1 expression; therefore, plays an antitumorigenic role in EAC.64 The combination of atuveciclib and 5-fluorouracil enhanced the downregulation of the MCL-1 protein in vitro, and they synergized in in vitro models as well as murine xenografts of EAC.64 Atuveciclib is the first highly selective CDK9 inhibitor to enter clinical trials (NCT02345382 and NCT01938638) for the treatment of cancer.117