RASSF1 and head and neck squamous cell carcinoma: Even lower frequencies of methylation have been reported in a heterogeneous HNSCC cohort, where DAPK1 methylation was detected in 12.5% (4/32) samples (excluding two samples with methylation additionally found in matched normal, indicating background methylation or contamination), and 0% (0/32) of samples demonstrated methylation of RASSF1A[36].