Altered tubulin structure in Rac1/Cdc42^−/− MKs. (A-B) Analysis of actin and tubulin structure by confocal microscopy. Representative stainings for actin (red), tubulin (green), and DAPI (blue) from at least 3 different samples per group are shown. (A) Visualization of proplatelets from wt (upper), Rac1^−/− (second), Cdc42^−/− (third), and Rac1/Cdc42^−/− (lower) MKs. Bar, 25 µm. (B) Start of proplatelet formation in mature wt (upper) and Rac1/Cdc42^−/− (lower) MKs. Bar, 25 µm.