Compared with adjacent normal tissues, the expression of the four genes (SERP1, CTSC, RAP2B, and SSR4) was significantly increased in ESCC patients (p < 0.001, p < 0.001, p < 0.001, p < 0.0001, respectively) (Figure 10A–D). Here, CTSC is linked to esophageal squamous cell carcinoma.