Changes in hematologic values after deletion of Mfrn1 in MX-Cre mice. Mice with the noted genotypes were injected with poly(I:C) to induce Cre recombinase. At times subsequent to induction of Cre, blood was taken for analysis of hemoglobin (HGB; A), RBC number (B), hematocrit (C), and MCV (D). Flow cytometric analysis of hematopoiesis in Mfrn1-knockout mice. Groups of Mx-Cre (Control) or floxed Mfrn1/Mx-Cre mice were treated with poly(I:C) and killed 8 weeks later for analysis of hematopoietic tissues. (E) Spleen cell suspensions were treated with ammonium chloride to lyse mature erythrocytes and evaluated for expression of the erythroid marker TER-119, which indicates erythroblast cells. (F-I) Bone marrow cell suspensions were isolated and evaluated for hematopoietic markers as indicated. (F) Selective gating for the hematopoietic stem and progenitor cell compartment (viable cells lacking expression of the lineage markers B220 and CD11b). Mfrn1-deleted mice exhibited increased numbers of erythroid progenitor cells (CD71⁺TER-119⁻). (G) Selective gating to exclude B220, CD11b, and TER-119⁺ cells. It can be seen that Mfrn1-deleted mice exhibit an increase in erythroid progenitor cells (c-kit⁺CD71⁺) and proerythroblasts (c-kit⁻CD71⁺). We also observed increased numbers of nonviable CD71⁺ cells (DAPI⁺CD71⁺; H) and decreased numbers of B-lineage cells based on B220 expression (I) in Mfrn1-deleted mice. Panels are representative of 6 Mfrn1-deleted mice and 9 control animals.