Par3 regulates the incidence of spontaneous NE ruptures. (A) Video stills taken from 2D-cell imaging of a representative RFP-expressing HeLa cell transfected with a mixture of lamin A– and lamin B1–specific siRNAs, showing transient NE rupture. Bar: 10 µm. See also Video 10. (B) Quantification of cells from A, indicating the percentage of cells showing transient NE rupture when transfected with siCTL or siPar3 before lamina protein depletion (means ± SEM [n = 4]; ****, P < 0.0001; ns, not signifcant. (C) Representative IB of lamin A/C, lamin B1, and Par3 depletion, as estimated by loading increasing amounts of control cell extracts (siCTL 1, 1/2, and 1/4); the graph shows quantification of Par3 and lamin protein levels (means ± SEM [n = 4]). The relative knockdown in each condition is calculated relative to the siCTL condition. (D and E) Working model on the role of Par3 and the LINC complex in controlling the spatial dynamics of actin filaments and force transmission to the nucleus in response to E4orf4. See Discussion for more details.