Transcriptional Hh-responsiveness of generated iMEFs. Indicated iMEFs were plated at confluence and treated ± Shh ligand. After 24 hrs, expression of Ptc1 was determined by Real-Time RT-PCR. A. Basal and Shh-induced expression of Ptc1. Values represent the mean ± SEM of 3–5 replicate experiments, * indicates P ≤ 0.05 (paired t-test). B. Ptc1 expression plotted as fold induction (Shh/Veh). Values represent the mean ± SEM of three replicate experiments. The letters above the bars denote the groups produced by the ANOVA pair-wise differences. Genotypes sharing a letter are not statistically significant at p ≤ 0.05 (Fisher's LSD).