Ligand activated PPARβ/δ-dependent increase in hepatic pro-fibrogenic marker expression. A) Sirus red staining of collagen fibers in liver sections from wild type (WT; top row) and PPARβ/δ-null mice (KO; bottom row). Mice were untreated (CTRL; 0.5% CMC; note that olive oil as control gave similar results) or treated with CCl4 or CCl4/GW501516 for 6 weeks. The far right panels are the samples stained with Martius/Scarlet/Blue to label fibrin in WT and KO mice treated with CCl4/GW501516. Sections are representative of six mice in each treatment group. Scale bar: 100 μm. B) qRT-PCR analysis shows pro-Col1 α1 (left) and pro-Col3 α1 (right) mRNA expression after 6 weeks of the indicated treatments in WT and PPARβ/δ KO mice. Results are means ± SD of at least three independent experiments performed in triplicate (* = p<0.05, Student's t-test).