Blebbistatin does not dramatically alter the morphology of CXCR4 positive endosomes. The cellular distribution CXCR4 without (A) and with blebbistatin treatment (B). C) Rab5 distribution with blebbistatin (80 μM, 1 hr). There was little change in the size or distribution of the CXCR4+ or endocytotic vesicles, despite a change in actin cytoskeleton stained with phalloidin (red, A vs. B and C). However, there was a qualitative increase in the amount of staining endosomes trapped throughout the cytoplasm in cells treated with blebbistatin (A vs. B).