CLAMP depletion has a non–cell-autonomous effect on CLAMP membrane localization and polarized cell division. (A) Ab staining of CLAMP mAb (green) and ZO-1 (red) reveal a strong association of CLAMP to the cell cortex. In mosaic tissues where CLAMP MO is marked with blue fluorescent protein (BFP, blue), CLAMP mAb staining is lost within and at the borders of CLAMP morphants and WT cells (blue; arrows) relative to WT–WT boundaries (arrowhead). (B) Quantification of fluorescent intensity of CLAMP mAb relative to ZO-1 Ab at the WT–WT boundary (n = 43), MO–MO (n = 42) and WT–MO (n = 82) cells in CLAMP morphant mosaic tissues. (C and D) Quantitative analysis (D) of the angle of cell division (representative image, C) measuring the CSD relative to the A-P axis in control MO (n > 500 cells from seven embryos), CLAMP MO (n > 300 cells from seven embryos) and Vangl2 MO cells (n > 700 cells from six embryos). In both B and D, error bars represent the SD, and p-values represent the t test (two-tailed, type 2). In all images, posterior is to the right. Bars, 5 µm.