NVP-2 is a potent and selective ATP-competitive cyclin dependent kinase 9 (CDK9) probe, inhibits CDK9/CycT activity with an IC50 of 0.514 nM. NVP-2 displays inhibitory effcts on CDK1/CycB, CDK2/CycA and CDK16/CycY kinases with IC50 values of 0.584 µM, 0.706 µM, and 0.605 µM, respectively. NVP-2 induces cell apoptosis.