We treated five different human HNSCC cell lines with the hypomethylating agent decitabine and assessed CTLA4 methylation via qMSP and CTLA-4 expression via quantitative reverse transcription PCR (qRT-PCR), flow cytometry, and immunohistochemistry (IHC) (Fig. 2). This evidence concerns the gene CTLA4 and head and neck squamous cell carcinoma.