Purity >95%. LEE011 is a cyclin-dependent kinase (CDK) inhibitor that targets cyclin D1/CDK4 and cyclin D3/CDK6 at nanomolar concentrations. It inhibits retinoblastoma protein phosphorylation, which prevents CDK-mediated G1 -S phase transition, arresting the cell cycle in the G1 phase, suppressing DNA synthesis, and inhibiting cancer cell growth. LEE011 has been shown to reduce proliferation in 12 of 17 human neuroblastoma-derived cell lines by inducing cytostasis (mean IC50 = 306 nM in sensitive lines).