Additional murine studies using prostate-specific conditional NKX3-1 knockout systems (NKX3-1flox/flox) alone or with concurrent PTEN deletion resulted in a phenotype resembling prostatic intraepithelial neoplasia (PIN) [16,17]; precursor lesions that are seen in patients prior to onset of adenocarcinoma [18]. Here, PTEN is linked to prostate intraepithelial neoplasia.