Retinoblastoma binding protein 2 (RBP2), a newly found histone demethylase, is overexpressed in gastric cancer. We examined the upstream regulatory mechanism of RBP2 at the microRNA (miRNA) level and the role in gastric carcinogenesis. We used bioinformatics to predict that microRNA-212 (miR-212) might be a direct upstream regulator of RBP2 and verified the regulation in gastric epithelial-derived cell lines. Overexpression of miR-212 significantly inhibited the expression levels of RBP2, whereas knockdown of miR-212 promoted RBP2 expression. Furthermore, we identified the putative miR-212 targeting sequence in the RBP2 3′ UTR by luciferase assay. MiR-212 inhibited the colony formation ability of cells by repressing RBP2 expression and increasing that of P21CIP1 and P27kip1, both critical in cell cycle arrest. In addition, the expression of RBP2 and miR-212 in tumor tissue and matched normal tissue from 18 patients further supported the results in vivo. MiR-212 directly regulates the expression of RBP2 and inhibits cell growth in gastric cancer, which may provide new clues to treatment. J. Cell. Biochem. 114: 2666–2672, 2013. © 2013 Wiley Periodicals, Inc.