PURA and esophageal squamous cell carcinoma: In addition, we also observed that there was more expression of PURα in the cytoplasm than in the nucleus in the ESCC tissues by immunohistochemical staining (n = 526) (Fig. 1D, E), and the protein fractionation analysis also indicated that PURα was additionally localized in the cytoplasm to a much greater extent than in the nucleus of ESCC cells (Fig. S1A).