Investigation of the role of Msln, Muc16, and Thy1 in fibrosis and fibroblast activation across multiple organs, demonstrated that Msln−/− mice are protected from cholestatic fibrosis caused by Mdr2 deficiency, bleomycin-induced lung fibrosis, and UUO-induced kidney fibrosis. Here, MUC16 is linked to pulmonary fibrosis.