The frequency of SFRP1 protein expression was low in human primary ESCC tumour, showing that SFRP1 protein was positive in 4.3% (3/70) of ESCC tumour tissues and no positive in the matched normal samples, as demonstrated in Supplementary Fig. 5a, b, SFRP1 exhibited positive expression in part clinical specimens and cell lines. This evidence concerns the gene SFRP1 and esophageal squamous cell carcinoma.