PROKR2 and prostate intraepithelial neoplasia: The degree of PIN varies from low-grade PIN (LGPIN) to high-grade PIN (HGPIN) where HGPIN lesions display multilayered luminal epithelium with greater elevation of proliferative markers such as Ki-67 and increased mitotic figures, as observed by phosphorylated histone H3 staining (p-HH3) [14,15].