NOS2 and idiopathic pulmonary fibrosis: Notably, immunofluorescent images showed that the expression of CD206 (a marker of M2 macrophage) rather than iNOS (a marker of M1 macrophage) had a significant increase in IPF patients compared with normal group (Figure 1D and S1C) and was positively correlated with SGK1 expression (Figure 1E).