EML4 and adenocarcinoma: In 2007, the chromosomal rearrangement involving the ALK and EML4 (echinoderm microtubule-associated protein like 4) genes was identified in about 5% of NSCLC patients [19]; the rearrangement is frequently observed in relatively younger patients, non- or light smokers, and those with adenocarcinoma histology without other genetic disorders, such as mutations of the epidermal growth factor receptor (EGFR) gene [20, 21].