CD24 and head and neck squamous cell carcinoma: Although CD24 satisfied our criteria for cancer-specific methylation with high-frequency methylation in cell lines, undetectable methylation in normal oral mucosa, and frequent methylation in primary OSCC tumor samples, we decided to eliminate CD24 from further experimental analyses because the information on the CpG probes for CD24 was not available for genome-wide methylation profiles from the TCGA HNSCC database.