Using RNA-sequencing data from The Cancer Genome Atlas, Martin et al. found that while TGFβ1 mRNA is the most prevalent isoform expressed in the majority of human cancers, certain cancer types, such as breast, mesothelioma, and prostate, are defined by high expression of both TGFβ1 and TGFβ3 mRNA30. Here, TGFB3 is linked to mesothelioma.