CSMD1 promoter methylation analyses by pyrosequencing revealed hypermethylation in 9 of 12 (75%) HNSCC cell lines with matching normal samples (and several other HNSCC cell lines without matching normal tissues) (Fig. 3a), 3 of 7 (~43%) PPOL cell lines (Fig. 3b), and 15 of 24 (~63%) primary HNSCCs (Fig. 3c). Here, CSMD1 is linked to head and neck squamous cell carcinoma.