According to the study that examined CpG island methylation around the promoter region of CDH-1 in HNSCC cell lines by methylation-specific PCR, the methylation was partially found in the HSC-2 cells, but not in the HSC-4 cells [46], which may also accounts for the low base-line expression of E-cadherin in the HSC-2 cells. This evidence concerns the gene CDH1 and head and neck squamous cell carcinoma.