Analyses of normal and abnormal fetal erythropoiesis by theG1-HRD-GFPtransgene. (A) Total (left) and c-Kit⁺ (right) cells from wild-type (top) and EpoR-null (bottom) E12.5 fetal livers with G1-HRD-GFP transgene were analyzed by FACS. The percentage in each quadrangle is shown. The means of the CD71 expression levels in the CD71⁺ fractions from each embryo are indicated by dotted lines. (B) Colony assay of sorted cells from G1-HRD-GFP transgenic fetal liver. (C) Result of the quantitative RT-PCR analysis of GATA-1 in EpoR^+/+::G1-HRD-GFP⁺ (closed bars) and EpoR^-/-::G1-HRD-GFP⁺ (hatched bars) fetal liver cell fractions. The GATA-1 mRNA levels were normalized to the level of GAPDH mRNA. The results are shown with standard deviations.