Endothelial cells in Apc-haploinsufficient mice block erythroid differentiation through IL6 secretion. qPCR analysis of c-Myc expression in MSCs (A) and endothelial cells (B) isolated from WT and Apc^+/− mice. (C-D) Flow cytometric analysis of erythroid cells in Lin⁻ BM cells cocultured with the endothelial cells from WT or Apc^+/− mice in erythroid differentiation medium. Gating strategy (C); summary data (D). (E) Cell pellets of Lin⁻ BM cells cocultured with the endothelial cells from WT or Apc^+/− mice in erythroid differentiation medium. (F) Detection of cytokines in the supernatant of WT and Apc^+/− endothelial cells. (G) Flow cytometric analysis of erythroid cells in Lin⁻ BM treated with different concentrations of IL6. (H) Flow cytometric analysis of erythroid cells in Lin⁻ BM cocultured with endothelial cells from WT, Apc^+/−, Apc^+/−cMyc^+/−, or c-Myc^+/− mice in erythroid differentiation medium. (I) Detection of IL6 concentration in the supernatant of WT, Apc^+/−, Apc^+/−cMyc^+/−, or c-Myc^+/− endothelial cells. *P < .05; **P < .01; ***P < .001, by Student t test.