Inhibition of Arp2/3 complex slows actin turnover at bleb membrane. (A) Decay of photoactivated Cherry-GFP^PA–β-actin shows actin turnover at the plasma membrane during bleb retraction. Image labels correspond to seconds post-GFP activation. (B) The heat map represents the GFP intensity at all points on the boundary of a single photoactivated bleb (shown in A) over its lifetime. Dotted lines represent the point at which the Cherry-GFP^PA–β-actin is activated. The decay rate of the activated GFP signal is approximately exponential. Data represent the analysis of a single bleb. (C) Rate of actin turnover, measured as the exponential decrease in photoactivated Cherry-GFP^PA–β-actin intensity, was significantly reduced in the presence of CK-869 (P < 0.05). Annotation above columns indicates results of Student’s t tests: n.s., not significant; *, P < 0.05; ***, P < 0.001. Error bars represent standard error of the mean. AU, arbitrary unit.