CDKN2A and neoplasm: To examine whether these findings were related to regional variability, we obtained separate tissue punches from p16 immunopositive and p16 immunonegative areas of the same meningioma tissue slide and found that even regions with p16 immunopositivity by IHC had CDKN2A deletion if the bulk tumor also had this deletion (Supplementary Fig. 10h-k).