Erythroid and myeloid differentiation block in MT1-MMP^−/− mice. (A) Real-time PCR of Epo in kidney (n = 3). (B-C) Percentage of different erythroblast populations during erythroid development (proE-EryA-EryB-EryC) of (B) BM cells or of (C) dissociated mouse spleen cells from MT1-MMP^+/+ (n = 5) and MT1-MMP^−/− mice (n = 3). (D) Percentage of CD11b⁺/Gr-1⁺ cells per femur as determined by FACS (n = 5). Errors in bar graphs are SEM; **P < .01. (E) Real-time PCR of G-CSF in BM cells (n = 3).