TGFB1 and Hepatic fibrosis: Overall, livers of Il15–/– and Il15ra–/– mice exposed to CCl4 upregulate collagen genes similarly to wildtype mice but show blunted induction of Tgfb and variable induction of matrix modifying enzyme genes and that the latter two may contribute to reduced liver fibrosis in IL-15 or IL-15Rα deficient mice compared to wildtype controls.