Low-grade and high-grade prostate intraepithelial neoplasia (PIN) lesions develop from normal prostate epithelium through the loss of phosphatase and the tensin homolog (PTEN), NK3 Homeobox 1 (NKX3.1), overexpression of MYC proto-oncogene, B-cell lymphoma 2 (BCL-2), and the glutathione S-transferase pi 1 gene (GSTP1), accompanied with Speckle Type BTB/POZ Protein (SPOP) mutation and Transmembrane Serine Protease 2- ETS-related gene (TMPRSS2-ERG) fusion [24,25,26,27,28,29,30,31,32,33,34,35,36]. The gene discussed is GSTP1; the disease is prostate intraepithelial neoplasia.