Hh signaling proteins localize to hESC primary cilia. (A) Localization of YFP:Smo (green) to the primary cilium (tb, red, arrow) in LRB003 hESCs. The merged image shows colocalization. Nuclei are stained with DAPI (blue). (B) Immunolocalization of Gli2 (green) to primary cilia (tb, red, arrows) in LRB003 hESCs. The merged image shows colocalization. Nuclei are stained with DAPI (blue). Gli data from H1 and LRB003 cells were obtained with different antibodies. (C) H1 cells grown for 7 d on matrigel in N2/B27-supplemented medium and labeled for primary cilia (tb, green) and anti-SHh (SHh, red). In addition, a z series of a field showing separate SHh labeling (red) located distinctly to the side of the primary cilium (green) is depicted. (D) Similar cells labeled with anti–Tra-1-85 (red) and anti-Gli2 (Gli2, green). Arrows indicate punctuate localization of the Gli2 protein (green dots) and the inset specifically localizes the Gli2 protein (arrowhead) at one end of a primary cilium (tb, red). (E) Anti-SHh (SHh, red) localizes near the base of most primary cilia. 33/71 cells possess primary cilia (46.5%), which is consistent with Fig. 1 C. 22/33 cells with primary cilia (66%) exhibit SHh near their base (arrows). SHh also localizes to points not associated with the cilia (arrowheads). The asterisk points to the midbody of cells that have recently undergone cytokinesis. These structures are not associated with Hh signaling molecules. (F) Anti-Smo (Smo, red) localizes predominantly to the base of primary cilia. This pattern of Smo expression is similar to that observed at 0 and 1 h of SAG stimulation (see Fig. 4). Arrows point to primary cilia (tb, green) and arrowheads indicate Smo localization.