CGNP cultures were generated as previously described (Kenney and Rowitch 2000). Cells were plated on individual poly-DL-ornithine (Sigma) pre-coated plates or pre-coated glass coverslips. In all cases cells were treated with 3 μg/mL of Shh. Where indicated, LY 294002 (Sigma) was used at a concentration of 10 nM for 6h.