BAP1 and mesothelioma: The critical role of normal levels BAP1 in preventing mesothelioma development is highlighted by multiple factors: (1) In families, BAP1 mutations specifically segregate among patients, while individuals who do not inherit the mutation are cancer free [5–9]; (2) tumors in carriers of germline BAP1 mutations always show loss of heterozygosity [5–9], i.e., biallelic BAP1 inactivation; (3) BAP1 is the most common acquired somatic mutation in sporadic mesothelioma [33–37].