Cdc42 deletion causes defective erythropoiesis. (A) Gross anatomy of bones from WT and KO mice. (B) Visualization of erythroid cells by benzidine staining (magnification × 1000). Slides were viewed with a Nikon Optiphot-2 microscope (Nikon, Melville, NY) using Plan Apo lens at 100×/1.25 oil and Cytoseal 60 mounting medium (Richard-Allan Scientific, Kalamazoo, MI). Images were acquired using a Spot camera model Insight 4 (Diagnostic Instruments) and were processed with Spot software version 4.0.9 (Diagnostic Instruments). (C) The total numbers of Ter119-positive erythroid cells in bone marrow were assessed at 14 DPI. (D) Flow cytometry analysis of CD71 and TER119 expression of freshly harvested bone marrow cells at 19 DPI, with percentages of erythroid cells at different developmental stages shown as in regions I to IV.