Runx1 deletion by Tg(vav-Cre) expression profoundly impacts the size and distribution of the MP compartment. (A) Schematic of the bi- and monopotent MPs that differentiate from the HSC/MPP compartment and can be distinguished by antigen markers.⁴⁴  (B) Representative FACS analysis to detect G/M and Meg/Ery progenitors performed on BM cells isolated from mice with indicated genotype. The genotype of the isolated fractions was confirmed by polymerase chain reaction (supplemental Figure 1A). (C) Bar graph showing the average number of MPs per mouse (2 femora, 2 tibia); n = 9 per cohort. Error bars, ± standard deviation (SD). (D) Total number of MP subpopulation per mouse is depicted by a dot, n ≥ 8 per cohort; horizontal line, median; error bars, ± standard error (SE). Total absolute BM cell counts were similar (1.03 × 10⁸ ± 0.20 × 10⁸ vs 1.06 × 10⁸ ± 0.20 × 10⁸ cells/mouse for Runx1^Δ/Δ versus Runx1^+/+ (n = 13 per genotype). (E) Relative distribution of progenitor types for each genotype based on a minimum of 8 mice per cohort. P values for panels D and E were calculated by a unpaired Student t test; n.s., not significant; **P < .05; ***P < .01. FSC, forward scatter.