Fig. 1: Cortical γ-actin is required for cytokinesis.

a Dividing HeLa cells fixed and stained with antibodies recognizing β-actin, γ-actin, DIAPH1, DIAPH3, and IQGAP1. b Quantitation of the number of multinucleated cells in the presence and absence of DIAPH1, IQGAP1, and DIAPH1-I862A that cannot nucleate actin. Bars denote the average, whiskers denote ±SD. *p = 0.0001, **p < 0.0001 to control using nonparametric two-tailed Mann-Whitney t-tests for three experimental repeats, n = 600 cells examined over three independent experiments. c β-actin or γ-actin localization in HeLa cells treated with control siRNA or DIAPH1 siRNA in the presence and absence of exogenously expressed GFP-DIAPH1 or GFP-DIAPH1-I862A. d Frames from time-lapse phase contrast movies demonstrating that depletion of DIAPH1 caused an increase in plasma membrane blebbing during anaphase. White arrows denote, blebs, black arrows point to the cytokinetic furrow. e Quantitation of the number of plasma membrane blebs in fixed metaphase and anaphase cells. Bars denote the average, boxes represent 25–75 percentile and whiskers denote extremes. *p = 0.014, **p = 0.0007, ***p = 0.0006, ****p = 0.0005, *****p = 0.0004 difference to control using nonparametric two-tailed Mann-Whitney t-tests for three experimental repeats, n = 300 cells examined over three independent experiments. CT = C terminus; DIA1 = DIAPH1; DIA3 = DIAPH3; IQ1 = IQGAP1. f Quantitation of the rate of cell elongation from 2–8 min after anaphase onset. Bars denote the average, whiskers denote ±SD. *p = 0.029, **p = 0.005, ***p = 0.0007, ****p = 0.0003, *****p < 0.0001 to control, using nonparametric two-tailed Mann-Whitney t-tests for three experimental repeats, n = 10 cells examined in each live-cell imaging group. CT = C terminus; DIA1 = DIAPH1; DIA3 = DIAPH3. Scale bars are 10 μm.