Rescue of I-2 knockdown phenotype by chemical inhibition of PP1 or HDAC. (A) ARPE-19 cells were transfected with siRNA as described in Figure 6. Cells were treated with 0.5 μM TSA or 0.5 nM calyculin A at 24 hr after siRNA transfection and 48 hrs later were fixed and immunostained for acetylated tubulin. Percentage of cells possessing a primary cilium with full or reduced levels of tubulin acetylation was counted as described in Figure 6. (B) Wide field images to show the acetylated tubulin staining (red) and DNA staining (blue) in cells treated with control siRNA, I-2 siRNA, I-2 siRNA + 0.5 nM calyculin A, or I-2 siRNA + 0.5 μM TSA. Scale bar represents 20 micron.