CDKN2A and glioblastoma: A number of tumor types display p16INK4a mutations, such as bladder carcinoma, pancreatic adenocarcinoma, non-small cell lung cancer, melanoma, glioblastoma, oropharyngeal cancer and OS.5 Specifically in OS, p16INK4a inactivation is observed in about 10% of tumors.52 The majority of p16INK4a alterations are deletions rather than point mutations.