The PP2A phosphatase promotes OSM-3 motility. (A) Ciliary defects in the let-92 mutant animals and cilia rescued with WT LET-92 or conditional knockout of nekl-3. The images of WT animals are the same as Fig. 2 D. Arrowheads indicate the junctions between the middle and distal segments. Scale bar, 5 μm. (B) Quantification of cilium length in animals of indicated genotypes. N = 39–58. Statistical significance, compared with the control with a matching color code, is based on Student’s t test. ***P < 0.001. Data are mean ± SD. (C) Representative fluorescence images of the amphid and phasmid cilia in the animals ectopically expressing let-92 at transition zone. Arrows indicate the ciliary base. Arrowheads indicate the junctions between the middle and distal ciliary segments. Scale bar, 5 μm. (D) Representative fluorescence intensity profiles along the cilium. All fluorescence intensity profiles are normalized to their maximum. N = 17–18 animals. Data are mean ± SD. (E) Statistics of the OSM-3 fluorescence intensity ratio (mean ± SD) between middle segment and distal segment in the indicated animals. Fluorescence ratio = 0.5*([mean gray value of middle segment area] − [background gray value])/([mean gray value of distal segment] − [background gray value]). N ≥ 32 animals. ***P < 0.001 by unpaired Student’s t test with Welch’s correction. (F) A proposed model for the regulation of regional motility of OSM-3 in vivo. t.z., transition zone; m.s., middle segment; d.s., distal segment.