Differentiation of Ter119⁻ FL erythroid progenitors ex vivo and the activation of the Hri signaling pathway. (A) Erythroid differentiation, and (B) reticulocyte production of Hri +/+ and −/− FL Ter119⁻ erythroid progenitors at 20, 40, and 60 hours of ex vivo culture. (C) Activation of Hri and protein expression of its downstream targets. Vertical lines have been inserted to indicate a repositioned gel lane. The middle 3 lanes, which contains Hbb^−/− samples, were removed of this Western blot because these results is not necessary for this figure. (D) qPCR analysis of the mRNA expression at 36 hours of ex vivo culture. Data are presented as relative expression normalized to eIF2α control with mean ± SD (n = 3; ***P < .005; **P < .01). Triplicate of ex vivo differentiation were carried out using Hri +/+ or −/− FL erythroid progenitors isolated from embryos of the same mother. This set of experiment was repeated 3 times with similar results.