(A) Expression of IL-4Rα in muscle progenitors (MPs), fibro/adipogenic progenitors (FAPs) and myeloid cells (CD11b+). (B) Time course of IL-4Rα expression in FAPs, MPs and CD45+ hematopoietic cells. (C, D) Expression of arginase 1 (Arg1) and iNOS (Nos2) mRNAs in regenerating TA muscles of wild type mice, n=4–6 per time point. (E) Fluorescent microscopy for Arg1 (red), Nos2 (green) and DAPI (blue) 2 days after muscle injury of WT mice (magnification, X400). (F) GFP staining of TA muscles of YARG mice after injury (magnification, X200). (G) TA muscles 8 days after injury in IL-4Rαf/f and IL-4Rαf/fLysMCre mice. (H) Representative day 8 muscle sections from IL-4Rαf/f and IL-4Rαf/fLysMCre mice stained with hematoxylin and eosin, n=6 per genotype. (I) Fluorescent microscopy of IL-4Rαf/f and IL-4Rαf/fLysMCre TA muscles 8 days after injury. Desmin in green and DAPI in blue. Error bars represent SEM. See also Figure S2.