NOS2 and hepatocellular carcinoma: In vivo study demonstrated that in diethylnitrosamine (DEN)-induced HCC, NOR1 is overexpressed in F4/80 positive macrophages and decreases M1-like markers (e.g., iNOS) and increases M2-like markers, such as arginase-1 (Arg1) and IL-10, thus promoting M2 polarization.