LEE011 (NVP-LEE011) is a highly specific inhibitor of CDK4/CDK6 and functions via decreasing in phosphorylated RB and FOXM1. When tested with 17 human neuroblastoma cell lines, 12 of them were sensitive to LEE011 treatment with mean IC50=306±68 nM. CDK4/6 could increase G1-S phase cell cycle progression and ultimately cellular proliferation via phosphorylating tumor suppressor protein RB. CDK4/6 signaling also could senescence suppression by regulating FOXM1 transcription. Numerous studies have shown that over-expression of CDK4/CDK6 correlated with tumorigenesis and disease progression.