Malignant mesothelioma cells with functional BAP1 were more sensitive to gemcitabine treatment compared to cells bearing mutated and non-functional BAP1. The results obtained from the analysis of cell viability indicate that functional BAP1 results in a better response to gemcitabine, that its status differentially affects the cell cycle progression in gemcitabine-treated versus non-treated cells and that BAP1 inactivation is linked to decreased DNA damage response after gemcitabine treatment. Here, BAP1 is linked to malignant mesothelioma.