FGF1 and head and neck squamous cell carcinoma: We investigated methylation of genes involved in FGFR signaling, namely FGFR1-4, the ligands FGF1-22, and also CCND1, which is co-localized with FGF3/4/19 at the 11q13 locus and has also been described to be overexpressed in HNSCC [23].