Effect of myosin II activity inhibition on ploidy of FPD/AML MKs. The ploidy level of CD41⁺CD42⁺ MKs was analyzed at day 10 of culture, 72 hours after addition of the myosin II inhibitor, blebbistatin. MK mean ploidy was calculated from the number of cells in each ploidy class. Blebbistatin was used at 25μM concentration. The significant increase in ploidy level after addition of blebbistatin was observed in 2 patients of pedigree A (A), 2 patients of pedigree B (B), and 2 patients of pedigree D (C; n = 6, P < .001).