Furthermore, zinc deficiency is associated with inflammation, increased miRNA-21 expression, the suppression of PDCD4 and an increased risk of esophageal squamous cell carcinoma (ESCC) (145), whereas, the upregulation of COX2- (146) and miRNA-21- (147) and the decrease in PDCD4 (135) expression correlates with worse Duke’s stage. Here, PDCD4 is linked to esophageal squamous cell carcinoma.