GLI1 and pancreatic neoplasm: S100A4 is an EMT indicator protein and might be an essential target gene mediated by Gli1 in pancreatic cancer.292,293 However, Lee et al. proposed that stromal response to HH signaling pathway is protective against PDAC and that HH signaling pathway activated by SAG21k can decelerate tumorigenesis.294 Perineural invasion is an important characteristic of pancreatic cancer with an incidence of 70–100%.