Expression of EpoR-tdTomato in BM and FL macrophages. (A) Flow cytometric analyses of EpoR-tdTomato in BM (left panels) and day 14.5 FL (right panels) macrophages showing expression of EpoR-tdTomato in subsets of BM and FL F4/80⁺ macrophages. (B) Flow cytometric analyses of the sorted BM F4/80⁺EpoR-tdTomato⁺ macrophages showing expression of F4/80 and EpoR-tdTomato but not Ter119 or Ly6G. (C) Composite representative cytospin images of the sorted BM F4/80⁺EpoR-tdTomato⁺ and F4/80⁺EpoR-tdTomato^– macrophages. Scale bar, 10 μm. (D) western blot analysis of pSTAT5 of the sorted macrophages stimulated with EPO showing dose-dependent phosphorylation of pSTAT5 in F4/80⁺EpoR-tdTomato⁺ but not F4/80⁺EpoR-tdTomato^–macrophages. N = 3.