EML4 and lung cancer: The gene rearrangement between the anaplastic lymphoma kinase (ALK) gene and echinoderm microtubule-associated protein-like 4 (EML4) gene resulting in the EML4-ALK gene fusion is the most common ALK fusion in lung cancer and are present in approximately 3-8% of NSCLC tumors, resulting in a constitutively active protein kinase that is essential for transformation [5, 6].