Atuveciclib (BAY 1,143,572)117, the first tolerable oral ATP-competitive CDK9 inhibitor, exhibited highly selective CDK9 inhibition (IC50 = 13 nM) in vitro under low ATP conditions (ATP concentration = 10 μM) and promising anti-proliferative potency toward several human cancer cell lines. The gene discussed is CDK9; the disease is cancer.