The staining of KLF4 was intensely at cell nucleus and cytosol in normal squamous epithelium of esophagus (a, b), representative expressions of KLF4 in ESCC were shown in (c–f) (Figure 5A) Then, we analyzed the relation between KLF4 expression and disease-free survival of the 38 patients. The gene discussed is KLF4; the disease is esophageal squamous cell carcinoma.