Altered actin polymerization underlies KDM3A mutant ciliary traits. (A) Wide-field images showing phalloidin-stained foci in KDM3A^null (line 2) when treated with 2 µM CytoD for 4 h +FCS. (B) Percentage of ciliated cycling cells in RPE1^WT and KDM3A^null (line 2) cultures in the presence of CytoD. Symbols represent the mean ± SD. Lines between symbols were added to ease visualization but are not in scale. (C) Single time frames (spanning ∼2 h) from live videos of RPE1^WT and KDM3A^null expressing 5HT6-EGFP in the presence of CytoD and FCS show instable mutant cilia (arrows). (D) Relative increase in ciliary lengths observed during 4 h of live imaging of RPE1^WT and KDM3A^null in the presence of CytoD and FCS. (E) Graphical summary: Depolymerizing actin increase ciliogenesis in cycling RPE1^WT cells. Conversely due to the already reduced number of actin fibers in KDM3A^nulls cells further depolymerization may induce ciliary instability and synthetic lethality. (F) Percentage of ciliated cells after resorption is induced by serum replenishment in the absence (DMSO) or presence of jasplakinolide for 80 min. Error bars represent SD (N = 3, number of cells scored indicated within each bar). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, not significant. (G) Images of cultures scored in F. (H) Graphical summary of jasplakinolide results.