OSR1 and prostate intraepithelial neoplasia: We observed 4 of 4 (100%) PtenloxP/loxP:Osr1-Cre mice to have developed high-grade PIN lesions in all glandular units of each prostatic lobe, including the anterior prostate gland (Fig. 2A1and 2A2), the dorsal/lateral prostate gland (Fig. 2B1 and 2B2), and ventral prostate gland (Fig. 2C1 and 2C2).