For example, PDCD4 has been reported to play a role as an inhibitor in AP-1 signaling pathway,36 and AP-1 signaling has been shown to activate miR-23a expression.37 Thus, AP-1/miR-23a/PDCD4 is likely to form a double-negative (overall positive) feedback loop that contributes to gastric cancer progression. This evidence concerns the gene PDCD4 and gastric cancer.