Pk1-Dvl2-CKII regulates cell cortical tension. (A) Schematic of cortical tensions β_A and β_B (arrows) and contributions θ_A and θ_B to contact angle of cell pair. (B) Homotypic Pk1-MO and heterotypic WT/Pk1-MO cell pairs showing straight and curved cell–cell boundaries, respectively. Pk1-MO cells labeled with blue dextran (d). B, bright field. Scale bars, 10 μm. (C) Relative cortical tension β_A/β_B in WT homotypic (n = 19), Pk1-MO homotypic (n = 16), and heterotypic (n = 14) cell pairs and small clusters (2–15 cells). n, number of cell pairs or clusters. ****, P ≤ 0.0001 in a two-tailed Student’s t test. Data distribution was assumed to be normal but was not formally tested. (D) Cell cortical tension β, tissue surface tension σ, and cell contact angle 2θ at the surface of a tissue. (E) An example of PCM aggregates, each from five to seven fused PCM explants, used to measure σ and 2θ. Scale bars, 100 μm. (F) Aggregate outlines (blue) and best-fit curves (red) generated by the ADSA program. (G) Measured parameters 2θ and σ and calculated cortical tension β. WT, n = 21; Pk1-MO, n = 8; Dvl2-MO, n = 17; Pk1-MO + Dvl2-MO, n = 6. Pk1-MO, 40 ng/bl; Dvl2-MO, 24 ng/bl. Means ± SD are indicated.