To elucidate causal link among CDKN2A/B homozygous deletion, CDK4/6 and fast glioma tumor cell proliferation, PDCs were derived from patient samples (Glioma #28: CDKN2A/B homozygous deletion, Glioma #17: WT) (Methods). The gene discussed is CDKN2A; the disease is glioma.