CSF1R and fibrosis: In the radiation-induced fibrosis (RIF) mouse model, IMs were first demonstrated to have a different role than AMs: Depletion of IMs with colony-stimulating factor receptor-1 (Csf1r) neutralizing antibody revealed a significant decrease in CD206+ IMs and alleviation of fibrosis symptoms, suggesting that IMs may play a pro-fibrotic role in the RIF processes through the CSF1/CSF1R pathway (66).