Liu et al. (2013) found that REG4 down-regulation also resulted in the hypoexpression of p21 and p27, which negatively regulated cyclin D1 and blocked the G1/S transition of prostate cancer cells. Wang et al. (2016) showed that transforming growth factor (TGF)-α stimulated specificity protein 1 (SP1) to transcriptionally promote REG4 expression, while G protein-coupled receptor 37 (GPR37) complexed with REG4, which mediated EGFR signal transduction by REG4 and promoted peritoneal metastasis of gastric cancer cells. This evidence concerns the gene EGFR and gastric cancer.