The probe is specific to NLGN4Y and does not detect NLGN4X mRNA, which shares 97% sequence homology with NLGN4Y. The results show that NLGN4Y is expressed in primary normal prostate epithelial cells (hPrEpiC), primary normal prostate fibroblast cells (HPrF) and prostatic intraepithelial neoplasia cells (PIN), but its transcript could not be detected in 8 of 11 cancer cell lines (i.e. VCaP, LNCaP 104S, MDA-PCa-2b, DU145, PC-3, PC-3M, ARCaPM and LNCaP 104R2) (Supplementary Figure S3). Here, NLGN4X is linked to prostate intraepithelial neoplasia.