FIGURE 3.

MFRN1 is required for primitive and definitive erythropoiesis in vivo. A, LacZ staining of gene trap Mfrn1^+/gt E8.5 yolk sac, showing erythroid-specific expression in sites of hematopoiesis. B, gross morphology of E11.5 wild-type (+/+) or gene trap (gt/gt) embryos. The mutant embryos were also stained for lacZ and have a profound anemia due to a defect in primitive erythropoiesis. C, erythrocytes and leukocytes from recipient, donor, or chimeric mice with medium or light penetrance (agouti coat color) were isolated and lysed, and isoforms were resolved on starch-cellulose gel electrophoresis and Ponceau-red stained for hemoglobin or glucose-6-isomerase (GPI). MFRN1-deficient donor-derived cells do not contribute to adult erythrocytes but do contribute to the myeloid lineage, indicating that MFRN1 is dispensable for myelopoiesis.