A univariate Cox analysis revealed that PFN2 protein level (HR = 2.669, 95 % CI = 1.147–6.209, P = 0.023), together with invasion depth (HR = 3.085, 95 % CI = 1.079–8.819, P = 0.036) and TNM stage (HR = 2.981, 95 % CI = 1.380–6.437, P = 0.005), was responsible for OS of ESCC patients (Table 5). The gene discussed is PFN2; the disease is esophageal squamous cell carcinoma.