A recent report revealed increased sensitivity of patients with proneural GBM to cyclin-dependent kinase 4/6 (CDK4/6) inhibitor treatment (Li et al., 2017) and significantly faster recurrence after bevacizumab treatment in patients with classic GBM (Hovinga et al., 2019), indicating the importance of careful evaluation of the subtypes before treatment. This evidence concerns the gene CDK4 and glioblastoma.