Inhibition of EZH2 accelerates acquisition of the MK surface markers, blocks MK proliferation at later stages, and decreases the mean ploidy of MKs. (A) H3K27me3 mean fluorescence intensity relative to immunoglobulin G control in different MK populations in the presence of GSK343 or GSK126 (n = 5). Data were compared using a Kruskal-Wallis test. (B) Representative flow cytometry plots of a violet dye experiment at day 4 of culture. Blue, dimethyl sulfoxide control (CTL); orange, GSK126; red, GSK343. The number of mitoses is indicated at the top of the figure. (C) Fold increase in the percentage of CD41⁺CD42⁺ cells in presence of EZH2 inhibitors. One representative experiment out of 3 experiments of flow cytometry analysis is shown. (D) Percentages of CD41⁺CD42⁺ cells at different days of culture. Data were compared using a Student t test with Mann-Whitney correction. CTL, n = 8; GSK126, n = 4; and GSK343, n = 8. (E) Proliferation curve of cord blood cells cultured in presence of TPO, SCF, and GSK343 or GSK126 or dimethyl sulfoxide (CTL) (n = 3) (left). Proliferation of GSK126- and GSK343-treated cells relative to the control at day 12 (right). Data were compared using 1-way analysis of variance with multiple comparison correction. All data represent means ± SEM. *P < .05. Ploidy of MKs treated with inhibitors (n = 5) (F) and transduced by 2 different shRNAs (n = 4) (G). Data were compared using a Student t test with Mann-Whitney correction. (H) Ploidy analyzed in a CD41^highCD42^high cell population. Flow cytometry of 1 representative experiment for MKs treated with inhibitors (i) and MKs transduced with 2 different shRNAs (ii). All data represent means ± SEM. *P < .05; **P < .005.