BCOR and neoplasm: One of the most frequently mutated genes in 17–32% of ENKTL cases is BCOR [28,40,41,42], a BCL-6 interacting corepressor which is involved in the epigenetic modification of histones via HDACs and which is suggested to be a tumor suppressor given frequent loss-of-function mutations seen in ENKTL [19,41] and enhanced cell proliferation and IL-2 production when BCOR is silenced [42].