For that purpose, MDR1 promoter methylation and P-gp expression was firstly assessed in a series of PCa, high grade prostatic intraepithelial neoplasia (HGPIN) – a precursor lesion of PCa – and non-tumorous prostate tissues [benign prostatic hyperplasia (BPH) and morphologically normal prostate tissue (NPT)]. The gene discussed is ABCB1; the disease is prostate intraepithelial neoplasia.