CDKN1A and esophageal squamous cell carcinoma: According to the criterion of Q values less than 0.01, remaining 10 upregulated (ANXA1, CDKN1A, ABL1, SCAMP3, EGF, LYN, MetAP2, VIM, TXLNA and FADD) and 13 downregulated (hK8, KLK13, ADAMTS15, hK14, GPC1, RSPO3, hK11, TRAIL, 5NT, CPE, TGFR2, SEZ6L and CD160) protein biomarkers in serum were authenticated as potential ESCC biomarkers.