PTCH1 and neuroblastoma: As expected, HIF-1α knockdown reduced SHH, PTCH1 and GLI1 transcripts levels in SH-SY5Y and IMR32 cells under hypoxia (all P < 0.0001) (Fig. 6C and D).The results of real-time PCR were consistent with those of Western blotting, suggesting that HIF-1α also regulated the SHH pathway through transcript levels in NB cells, further influencing protein expression.