Abnormal cytoskeleton in DKO megakaryocytes. (A) Representative thin-section electron micrographs of fetal liver–derived megakaryocytes from (i,ii) WT and (iii,iv) DKO embryos. (B) Phalloidin staining of fetal liver–derived megakaryocytes (top) and quantification of F-actin (bottom) show decreased polymerized actin in DKO (***P < .001; all error bars represent SEM).