Par3 depletion inhibits E4orf4 tumoricidal phenotypes. (A) Representative IBs of Par3 depletion in U2OS cells (shPar3A and B) and HeLa cells (siPar3-3 and 3-9), as estimated by loading increasing amounts of control extracts (shCTL or siCTL, 1, 1/2, and 1/4); GAPDH, loading control. (B) The percentage of cell blebbing and nuclear condensation, as scored relative to RFP- or E4orf4-mCherry-expressing cells at 24–36 h after transduction; data from one representative experiment (shPar3A) or means ± SEM (n = 3). (C) Quantification of the nuclear circularity index of cells treated as in B (means ± SEM [n ≥ 43 cells; n ≥ 3]). (D) Representative IBs of extracts from HeLa cells treated with siRNAs and then transfected with the vector (EV) or E4orf4-mRFP (WT); activated myosin II, phospho-MLC2 (T18 and S19); total myosin II, MLC2; GAPDH, loading control. Quantification represents means (n = 2; HeLa cells) or means ± SEM (n = 4; 293T-shPar3#4 cells). (E) Quantification of the N/C ratio of E4orf4-mCherry in HeLa cells transfected with siCTL or siPar3 for datasets represented in Fig. S4 B (means ± SEM [n ≥ 118 cells; n = 3]). **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns, not significant. See also Fig. S4 B.