Pk2 promotes AJ remodeling and cell intercalation in the gastrula ectoderm. (A and B) Representative snapshot images of Xenopus gastrula ectoderm. GFP-ZO1 only (A) and GFP-ZO1 with Flag-Pk2 (B). Time-lapse imaging was initiated at stage 11. The white circles indicate T1 junctions. (C) Rate of cell intercalation in the control or Pk2 ectoderm. Individual dots represent the average rates of cell intercalation in individual embryos. Unpaired Student’s t test (two-sided) was used to compare the means. Data distribution was assumed to be normal, but this was not formally tested. Three embryos per experimental group were used. The total number of cells was as follows: n = 73 (control); n = 114 (Flag-Pk2). (D and E) Representative images of AJ tracking in control GFP-ZO1–only (D) or GFP-ZO1 with Flag-Pk2 OE (E) ectoderms. Asterisks indicate cell division. (F) Representative changes in AJ length. The plots included 6 AJs (control) and 14 AJs (+Flag-Pk2) from one embryo. (G) Calculated rates of AJ length change on the basis of data in F. (H and I) Rates of AJ elongation (H) and shrinkage (I) on the basis of 2 h and 42 min’ tracking of 30 AJs (control) and 34 AJs (+F-Pk2). AJs were randomly selected from three embryos per group. The total number of AJ length changes in H and I was as follows: n = 1,836 (control); n = 1,729 (+F-Pk2). The bold and thin lines represent the medians and quartiles, respectively. The Mann‒Whitney U test was used to compare the mean ranks. *P < 0.05, **P < 0.01. Scale bars: 20 μm.