SMAD4 and head and neck cancer: To create an in vitro cellular model of head-and-neck cancers, we selected three head-and-neck-cancer-cell lines from different locations (Detroit 562: pharynx, FaDu: hypopharynx and SCC25: tongue) harboring different genetic mutations (Detroit 562: TP53, CDKN2A and PIK3CA mutations, FaDu: TP53, CDKN2A and SMAD4 mutations and SCC25: TP53 and CDKN2A mutations) [14].