We then showed that the expression of the most functionally related gene, Pten, was also down-regulated in the ESCC-bearing ZD3T esophagus that overexpressed miR-21 at the mRNA level by qPCR (P = 0.02, n = 6 rats/group) and at the protein level by immunohistochemistry compared to ZS counterpart (Figure 7C). Here, PTEN is linked to esophageal squamous cell carcinoma.