FZD9 and esophageal squamous cell carcinoma: In contrast, the transcriptional levels of FZD2, FZD8 and FZD10 were only upregulated in several ESCC cell lines, while the expression levels of FZD3, FZD5, FZD6 and FZD9 in most of the ESCC cell lines were similar to the two normal esophageal epithelial cells.