The BRCA1 Associated Protein 1 (BAP1) gene (located on chromosome 3p21.1) encodes a nuclear deubiquitinating enzyme (DUB) functioning as a potent tumor suppressor. As part of the Polycomb repressive deubiquitination complex (PR‑DUB), BAP1 regulates key cellular processes including cell cycle progression, DNA damage repair, ferroptosis, and chromatin modulation. Inactivating germline or somatic mutations in BAP1 significantly predispose individuals to various cancers, most notably malignant mesothelioma, uveal melanoma, clear cell renal cell carcinoma, and specific types of cutaneous melanoma (BAP1‑inactivated melanocytic tumors). BAP1 mutation status is increasingly recognized as a critical factor for cancer risk assessment, prognosis, and potential therapeutic targeting.