EPO promotes proliferation of EpoR-expressing cells in vivo. (A) Left panels: flow cytometric analyses showing the proportion of EpoR-tdTomato⁺ and EpoR-tdTomato^– populations within lineage^– cells with phosphate-buffered saline (PBS) or EPO injection; right panels: flow cytometric analyses showing Edu⁺ cells of EpoR-tdTomato⁺ and EpoR-tdTomato^– cells with PBS or EPO injection. Flow cytometric analyses displaying proportion of Edu⁺ cells in BFU-E (B), CFU-E (C), Pro (D), Baso (E), MEP (F), GMP (G), CMP (H), CD19⁺ B cells (I), and CD41⁺ megakaryocytes (J) with PBS or EPO injection. N = 3. *P < .05; **P < .01; ***P < .001. FSC-H, forward scatter height; N.S., not significant.