mDia2 is essential for the mobility of R1 reticulocytes. (A) Time lapse real-time microscopy of enucleating erythroid cells derived from cultured bone marrow erythroblasts obtained from the indicated mice. Still frames of cells at the indicated times (seconds) are shown. The bottom panels show an enucleating cell with 2 extruding nuclei. Nuclei were stained with NucRed Live 647. Bars represent 1 μm. White dots outline R1 reticulocytes. Far right panels show the overlapped outlines of the dynamic reticulocytes at different time points. (B) Scanning electron microscopy analyses of enucleating cells from panel A. (C) Mean corpuscular volume of RBCs from peripheral blood of the indicated mice at 1 month of age. (D) Wright-Giemsa–stained peripheral blood smears from the indicated mice at 1 month of age. Bar represents 10 μm.