Abnormal F-actin redistribution in WAS MKs. Cultures were performed as described in Fig 1. At day 8, cells were fixed and, after cytocentrifugation, were incubated with anti-vWF (TRITC) to localize the MKs (B and E) and with phalloidin (FITC) to study F-actin distribution (C and F). DNA was stained by Hoechst dye (A and D). In normal MKs (A, B, and C), F-actin distribution was located linearly under the cytoplasmic membrane and regularly distributed (C), while in WAS MKs (D, E, and F), F-actin was localized in the center of the cell (F).