TGFB1 and hepatocellular carcinoma: In addition, we analyzed the expression of the TGF-β, MMP2, TIMP2, and p21 cell fibrosis signaling protein markers by Western blotting after exposing the HepaRG and HCC HepG2 cells to 2-ET, 3-ET, and 4-ET alone (Figure 5C, left panels) or in a combination of 2-ET+3-ET, 2-ET+4-ET, 3-ET+4-ET, and 2-ET+3-ET +4-ET as indicated (Figure 5C, right panels).