CD163 and hepatocellular carcinoma: To explore whether the three different macrophage activation states are correlated with hepatocarcinogenesis over time in the primary rat HCC model, the expression of CD68 (M0 macrophage marker), iNOS (M1 macrophage marker), and CD163 (M2 macrophage marker) were detected by immunohistochemical analysis at different times point (Additional file 1: Fig. S4A).