CDK4 and cancer: CDKN2A SCND leads to inactivation of both P16INK4a and P14ARF (two endogenous inhibitors for CDK4 and MDM2) in >90% CDKN2A-deleted cancers, it needs to study whether CDK4 and MDM2 inhibitor drugs could be used to prevent hematogenous metastasis of cancers.