RECK mRNA expression and promoter methylation in patients with ESCC. (A) RECK mRNA expression was lower in ESCC patients with ∆MI >0.16 compared with those with ∆MI ≤0.16. Statistical analyses were performed using the unpaired t-test. (B) The scatter plot shows that the mRNA expression level of RECK (−∆Cq) was significantly associated with the MI in ESCC tissues. (C) The scatter plot shows that RECK mRNA expression (−∆∆Cq) was significantly associated with ∆MI in ESCC patients. (D) The scatter plot shows that the mRNA expression level of RECK (−∆Cq) was not significantly associated with the MI in non-tumor tissues. Statistical analyses were performed using Pearson's correlation coefficient test. -∆∆Cq, -(∆CqESCC - ∆CqNon-tumor); ∆MI, MIESCC - MINon-tumor; MI, methylation index; RECK, reversion-inducing cysteine-rich protein with kazal motif; ESCC, esophageal squamous cell carcinoma.