SMAD4 and head and neck squamous cell carcinoma: Also, Lepikhova et al. genetically profiled 45 human HPV-negative-HNSCC cell lines under the effect of 220 anticancer drugs that had been established at the Department of Otorhinolaryngology-Head and Neck Surgery, in Turku University Hospital [11], These and other studies show that TP53, CDKN2A, CDKN2a(p14), SMAD4, PIK3CA, mTOR, NOTCH or EGFR are the most common mutated genes in HNSCC cell lines [9–12].