JNK activity is necessary for ciliary function. (A) Quantification of the fluid flow with fluorescent beads in DMSO- and SP600125-treated (2 h) embryos. SP600125 was added into the media of embryos after MCC differentiation was completed, at stages 31–34. Error bars indicate ± SEM from two independent experiments, n = 5 embryos per group, ***, P < 0.001, unpaired two-tailed t test. Scale bar, 500 μm. (B) Immunofluorescence images showing Xenopus epidermal MCCs labeled for F-actin (Phalloidin) and cilia (anti-acetylated α-tubulin) after exposure to DMSO or SP600125 for 2 h. Scale bars, 20 µm. Quantification shows decreased acetylated tubulin intensity (n = 63 DMSO, n = 70 SP600125) and apical cell surface in SP600125-treated embryos (n = 107 MCCs) compared with DMSO (n = 87). Error bars indicate ± SEM from three experiments. ***, P < 0.001, unpaired two-tailed t test. (C) Higher magnification images of 2 h DMSO- and SP600125-treated MCCs stained for Phalloidin and acetylated α-tubulin. The apical and subapical actin networks in SP600125-treated embryo are impaired. Scale bars, 10 µm. (D) RFP-Centrin injected embryos were treated for 2 h at stage 30 with either DMSO- or SP600125. Quantification of basal body distribution by measuring the distance of individual basal bodies relative to their nearest neighbors (n = 140 basal bodies for each condition from three embryos). Error bars indicate ± SEM from three experiments. ***, P < 0.001, unpaired two-tailed t test.