PGK1 and esophageal squamous cell carcinoma: Furthermore, several proteins related to glycolysis, such as PKM, PGK1, ALDOA and LDHB, were significantly elevated in the serum of ESCC patients and positively correlated with TNM stages (R2 = 0.31, P = 0.001, R2 = 0.37, P = 3.7e−4, R2 = 0.34, P = 7.0e−4, and R2 = 0.39, P = 1.8e−4, respectively), which suggested activated glycolysis could be a significant characteristic of ESCC.