Attenuated splenic stress erythropoiesis in EpoR-HM mice in response to phenylhydrazine-induced anemia. EpoR-HM and wt-EpoR mice were treated at 0 and 24 hours with phenylhydrazine. At 120 hours, spleens were isolated, photographed, weighed, disrupted, and analyzed for Ter119 expression. Plotted values are spleen weights (mg) and direct frequencies of Ter119-positive splenic EPCs from 4 EpoR-HM and 4 wt-EpoR mice. The significance (P values) of differences between overall mean values (horizontal bars) was tested using Student t distribution.