ALK and lung adenocarcinoma: First, besides EGFR mutation, there are several molecular alterations involved in lung adenocarcinoma carcinogenesis, including v-raf murine sarcoma viral oncogene homolog B (BRAF), Kirsten rat sarcoma viral oncogene homolog (KRAS), human epidermal growth factor receptor 2 (HER2), and echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK).