Palbociclib D8 is a deuterium labeled Palbociclib. Palbociclib is a selective and orally active inhibitor of CDK4 and CDK6 (IC50s of 11 and 16 nM, respectively).
PD0332991, an unsymmetrical indolocarbazole compound, is cell-permeable and exhibits antiproliferative effects by functioning as a potent, selective, reversible, and ATP-competitive inhibitor of Cdk4 D1 (IC 50 = 76 nM). Although it can inhibit other Cdks, such as Cdk2 E and Cdk1 B, effectiveness requires higher concentrations (IC 50 = 520 nM and 2.1 µM, respectively) and demonstrates minimal activity against CaMKII, PKA, or GSK-3β (IC 50 ≥ 12.4 µM). PD0332991 efficiently inhibits tumor cell growth in HCT-116 and NCI-H460 cell lines with an IC 50 < 3.0 µM, primarily through blocking Rb phosphorylation and inducing G1 cell cycle arrest.