 These mice exhibit elevated erythropoiesis consistent with the idea that phosphatase recruitment (and therefore the shutting down of signaling) is aberrant in these mice.The EpoR-HM receptor also lacks the majority of the cytoplasmic domain, and contains the tyrosine 343 that was mutated to phenylalanine, making it unsuitable for efficient Stat5 docking and activation.These mice are anemic and show poor response to hypoxic stress, such as phenylhydrazine treatment or erythropoietin injection.