CDK4 and glioblastoma: To provide further evidence for the application of CDK4/6 inhibitor in GBM treatment, efficacy of a combination of palbociclib and c-Met inhibitor, such as volitinib (Gavine et al., 2015) will be focused, which will also offer the foundation that with c-Met inhibitor, CDK4/6 inhibitor can also be applied for treating GBM with PTEN deficiency.