IFT is normal in arl13 mutant cilia. (A) Western blot of isolated control (g1, WT) and arl13 cilia probed with antibodies against IFT81, IFT139, BBS4, D1BLIC, KAP, ARL13, and, as a loading control, IC2. The quantification of the band strengths normalized for those of IC2 are shown in brackets. The analysis is based on several membranes with equal loading; the lanes stained with anti-ARL13 and anti-IC2 were also used for the Western blot shown in Fig. S2 E. (B) Immunofluorescence staining of control (g1; a–c) and arl13 (d–f) cells with antibodies to acetylated tubulin (a and d) and IFT54 (b and e). Merged images are shown in c and f. (C) TIRF images and corresponding kymograms showing IFT in ift54 mS-IFT54 and arl13 ift54 mS-IFT54 cilia. Anterograde IFT results in trajectories from the bottom left to the top right whereas top left to bottom right trajectories result from retrograde IFT. The ciliary tips (T) and bases (B) are indicated. Bars = 2 µm and 2 s. (D) Violin plot of anterograde and retrograde velocities of mS-IFT54 in ift54 mS-IFT54 and arl13 ift54 mS-IFT54 cilia. The P values of a two-tailed t test are indicated. N, the number of IFT trains analyzed. (E) Violin plot of the anterograde and retrograde IFT frequencies of mS-IFT54 in ift54 mS-IFT54 and arl13 ift54 mS-IFT54 cilia. The P-values of a two-tailed t test are indicated. N, the number of cilia analyzed. Source data are available for this figure: SourceData F2.