Increased cyclin B1 levels mediate adhesion disassembly in G2 phase. (A and B) Immunofluorescence images of control or cyclin B1–knockdown cells stained for paxillin and actin (A), and quantification of adhesion complex area changes in G1, S, or G2 phase for control, cyclin B1–, and cyclin B2–knockdown cells (B). A minimum of 43 cells per condition was used for analysis. Bars, 10 µm. (C) Western blot of CDK1-Y15 phosphorylation for Wee1 inhibitor (MK1775)-treated cells in G1, S, and G2, and quantification of adhesion area changes across the cell cycle with cells in G1, S, and G2 being treated with either DMSO or MK1775 for 2 h. Molecular masses are given in kilodaltons. (D) Quantification of adhesion area changes in G1, S, and G2 cells being treated with either DMSO or MK1775 for 2 h. (E) Quantification of adhesion area changes in G2 cells being treated with either DMSO or MK1775 for 2 h after knockdown of either cyclin A2 or cyclin B1. (F and G) Quantification of HeLa cell rounding and successful division for control and cyclin B1–knockdown cells. A minimum of 2,348 cells per condition was used for analysis. (H) Quantification of HeLa cell Ferret’s diameter as cells enter mitosis in control (36 cells) and cyclin B1–knockdown cells (35 cells). Results in B and D–G are displayed as Tukey box and whisker plots (whiskers represent 1.5× interquartile range) and are for at least three biological replicates. *, P < 0.05; **, P < 0.01; ****, P < 0.0001.