KRAS and lung cancer: A variant allele in the K-Ras 3-untranslated region, which arises in the let-7 miRNA complementary site (K-Ras-LCS6) and leads to increased K-Ras expression in lung cancer [36], was shown to significantly reduce survival time in squamous cell carcinoma of the head and neck, suggesting that this variant may alter the phenotype or therapeutic response of the disease [37].