Two normal oesophageal fibroblast (NEF) cell lines, designated NEF3 and NEF4 (established from normal oesophageal tissue of patients who underwent surgical resection of primary oesophageal tumour), which had confirmed fibroblastic phenotype (Supplementary Fig. 1d), were used to test the paracrine effects of ESCC cells on fibroblasts. This evidence concerns the gene PRPH and esophageal squamous cell carcinoma.