a, b, GSN knockdown reduced ciliated cell numbers. a, d, ACTR3 knockdown increased the number of cells with longer cilium (> 6 μm). c, e, Western blots showing protein levels (†GSN siRNA#1 was cytotoxic). f, ACTR3 knockdown induced ciliogenesis without serum starvation. g, CytochalasinD treatment for 8 hrs increased ciliated cell numbers without serum starvation. h, Ciliogenesis defect by GSN knockdown was rescued by 8 hr cytochalasinD treatment. i, Live imaging of htRPE-SmoEGFP cells after 60 hr siRNA transfection. Arrowheads, the pericentrosomal preciliary compartment (PPC) at the ciliary base. j, Morphology of PPC. Gamma-tubulin labels the centrosome. k, Live imaging of a PPC positive cell in serum-free medium. l, Live cell imaging in serum-free medium containing DMSO or cytochalasinD. Values, mean ± SD [n = 4 (b,d), 2 (f) and 3 (g,h)]. Student's t-test: *P < 0.05, **P < 0.01. Scale bars, 10 μm (a); 5 μm (i,l); 2.5 μm (j,k).