All core PRC2 components restrict HSC/progenitor activity. (A) The 3 PRCs, displaying mammalian components, Drosophila counterparts (shown in italics), and enzymatic activities. (B) Peripheral blood platelet (top panels) and white blood cell counts (bottom panels) at 7 weeks of age from mice of the given genotypes. The horizontal bar marks the mean for n = 20 to 25 samples per genotype. Eed³³⁵⁴ mice were on a mixed genetic background. (C) Bone marrow cells from 3 CD45^Ly5.2 donor mice of the given genotype were mixed with Ezh2^+/+Mpl^−/−CD45^Ly5.1 competitor cells at 1:1 (left) or 1:10 (right) ratios and used to reconstitute 3 lethally irradiated recipients per donor. Contribution of test cells is shown at 10 to 16 weeks after reconstitution. Blood indicates peripheral white blood cells; and Mϕ, macrophages. Statistical significance: *P < .05, **P < .01, ***P < .001, corrected for multiple testing; error bars indicate SEM.