Proplatelet development and stress fiber formation are rescued after inhibition of RhoA pathway. (A) Stress fiber formation assessed at day 15 or 16 of MK differentiation in presence and absence of ROCK1/2 inhibitor Y-27632 for the edited clones: WT and del3 (n = 5), mutant (n = 6), del1 and del2 (n = 3), and del4 (n = 4); paired Student t test. (B) Proplatelet formation potential in presence and absence of ROCK1/2 inhibitor Y-27632 for both patients’ iPSC clones (n = 3); paired Student t test. (C) Proplatelet formation potential in presence and absence of ROCK1/2 inhibitor Y-27632 in all edited clones: WT (n = 6), mutant (n = 8), mutant + WT, del1, del3, and del4 (n = 4), and del2 (n = 3); paired Student t test. The ROCK1 inhibitor was added at day 15 to culture, and proplatelet formation was measured at day 18. *P < .05, **P < .01, ***P < .001.