SMO and prostate intraepithelial neoplasia: These data are in agreement with earlier studies that have revealed an increase of expression levels of hedgehog signaling components (SHH, patched (PTCH) receptor, smoothened (SMO) co-receptor, GLI-1 and/or GLI-2 transcription factors) were detected in some cases of high-grade prostatic intraepithelial neoplasia (PINs), PC tissues and bone metastases relative to normal prostate and adjacent non-malignant human prostate tissues [12, 13, 15–19].