Relationship between DDR1 repression and CCL4-induced liver fibrosis. Mouse liver tissue stained with (A) H&E, (B) Masson, and (E) DDR1; n = 6. Original magnification: ×100. (C) Quantification of Masson-positive areas in liver sections. (F) Quantification of immunostained areas in liver sections. (G) Representative immunoblot and quantification of DDR1 protein levels; n = 4. β-Tubulin was used as a loading control. (H) Gene expression of DDR1 in mouse livers via RT-qPCR; n = 3. (D) Relative ALT and AST activities in serum from WT and DDR1-KO mice after being treated with CCl4; n = 6. Data are expressed as mean ± standard deviation. *P <0.05, **P <0.01, and ***P <0.001.