TGFB1 and Hepatic fibrosis: These results suggest less liver fibrosis development upon deletion of a single copy of Mll4. At the mRNA level, Mll4 deletion caused a robust reduction in the expression of genes associated with fibrosis, including Acta2 (α-SMA), Timp1, Tgfβ1, and Col1a1 as measured by qRT-PCR (Fig. 2D).