Inhibition of Rho, ROCK, and MLCK decreases MLC2 phosphorylation while increasing PPF. The Rho inhibitor Tat-C3 (10 μg/mL), ROCK inhibitor Y27632 (10 μM), or MLCK inhibitor P18 (50 μM) alone or in combination with Y27632 was added at day 10 to CD41⁺ MKs derived from leukapheresis. (A) PPT quantification on day 11 showing a significant increase of PPT with all these inhibitors. Three independent experiments were performed (t test; P < .04). Error bars indicate SD. (B-D) Western blot performed on the CD41⁺ MKs treated for 24 hours either with Tat-C3, Y27632, or P18 showing a partial inhibition of pMLC2. An additive effect was observed in combination P18 with Y27632.