CDK4 and glioma: The IC50 values indicated that PD-0332991 (which targets cyclin-dependent kinase 4/6, CDK4/6), axitinib (an inhibitor of VEGFR), BIBW2992 (an irreversible inhibitor of the ErbB family of tyrosine kinases), BIRB0796 (an inhibitor of mitogen-activated protein kinase, MAPK), and gefitinib (an inhibitor of epidermal growth factor receptor, EGFR) might be alternatives in treating gliomas in the high-risk group (Figure 6H).