Representative images of Shh (A–C), Smo (D–F), Ptch (G–I) and Gli1 (J–L) expression in non-neoplastic peripheral zone (D, G, J), low-grade prostate carcinoma [Gleason scores 6 and 7 (3+4)] (A, B, E, H, K) and high-grade carcinoma [Gleason scores 7 (4+3), 8 and 9] (C, F, I, L). Arrows in A and B depict the non-neoplastic epithelium. Note that epithelial Shh (A–C), Smo (D–F) and Ptch (G–I) expression is increased and stromal expression is decreased in tumours compared to non-neoplastic tissue. Ptch expression is increased in epithelial cells and decreased in stromal cells of high-grade compared to low-grade tumours (H, I). Stromal expression of Gli1 (J–L) is down-regulated in carcinomas compared to peripheral zone tissue.