GLI1 but not S6K1 knockdown reduces GLI1, GLI2, GLI3, SMO and PTCH2 expression. The expression of S6K1 (A), GLI1 (B), GLI2 (C), GLI3 (D), the signaling molecule SMO (E) and the typical GLI1 target gene PTCH2 (F) in SK-N-AS cells, following siRNA knockdown of GLI1 and S6K1, was determined by real-time PCR. Data are represented as relative expression (2-∆∆Ct values), calculated by subtracting the Ct value of the housekeeping gene TBP from the Ct value of the interrogated transcripts (∆Ct), and normalized to the ∆Ct value obtained with siCN. Error bars indicate the standard deviation. *, Statistical significant, P < 0.02 compared to control, calculated by the Student’s t-test.