Epo-dependent PPARγ signaling promotes SEP differentiation. Analysis of the effects of manipulating PPARγ signaling in in vitro stress erythropoiesis cultures. Unfractionated bone marrow cells were cultured in SEEM or SEDM with indicated treatments.(A) Flow cytometry analysis of in vitro cultured SEPs in SEEM with or without 1 μM Pio. Percentage of CD34⁺CD133⁺KS SEPs and CD34^–CD133^–K⁺S^– SEPs in total cell population (left). Total cell numbers after culture (right). (B) Flow cytometry analysis of in vitro cultured SEPs in SEDM with or without 1 μM GW. Percentage of CD34⁺CD133⁺KS SEPs in total cell population (left). Total cell numbers after culture (right). (C) Stress BFU-E colony assay of in vitro cultured SEPs expanded in SEEM and then treated with Epo, Pio, GW, or HQL-79 as indicated. Student t test (2-tailed). Data represent means ± SEM. *P < .05; **P < .01.