These investigations have demonstrated that exposures to very low doses of crocidolite (total 0.1–0.5 mg, compared to 3–5 mg generally used in such experiments) induced mesotheliomas in 36–47% of heterozygous Bap1-mutant mice versus about 10% of similarly exposed WT littermates. The gene discussed is BAP1; the disease is mesothelioma.