To assess the role of PYCR1 in ESCC tissues, we acquired its expression profile in 182 EC tissue samples and 286 normal tissue samples from GEPIA database (http://gepia.cancer-pku.cn/index.html), and found that the mRNA of PYCR1, a key rate limiting enzyme in proline metabolism, was significantly up-regulated in EC tissues compared with normal tissues (Fig. 7A). This evidence concerns the gene PYCR1 and esophageal squamous cell carcinoma.