Based on IHC results, we decided to use the MSTO-211H cell line, established from the pleural effusion of a patient with biphasic mesothelioma, as a model to better characterize in vitro the response of BAP1 wild-type MPM to EPZ-6438, a potent and selective inhibitor of the H3K27 methyltransferase EZH2. The gene discussed is BAP1; the disease is mesothelioma.