GRM2 and carcinoma: Likewise, immunohistochemistry with an anti-GluR2 antibody showed a significant difference in the positivity of staining that was uniformly present in virtually 100 % of benign secretory prostatic epithelium when compared with a high-grade prostatic intraepithelial neoplasia and low Gleason-patterned carcinomas where scarcely any or very low immunoreactivity of GluR2 was observed.