CDK6 and cancer: Because CDK4 plays an important role in G1/S phase transition by associating with CDK6 [31-33], deregulation of the CDK4/6 signaling pathway is one of the most common changes found in human cancers [34-36], including NSCLC [37, 38], CDK4/6 were also considered the most desirable targets for cancer therapies [39-41].