Roniciclib binds to and inhibits the activity of CDK1/Cyclin B, CDK2/Cyclin E, CDK4/Cyclin D1, CDK6/Cyclin D3, and CDK9/Cyclin T1, which are serine/threonine kinases playing key roles in the regulation of tumor cell proliferation and survival. This evidence concerns the gene CDK9 and neoplasm.