EML4 and lung adenocarcinoma: ALK rearrangements occur in 3–5% of lung adenocarcinomas [21], consequent to an inversion on the short-arm of chromosome 2 joining its 3′ end with the 5′ end of the echinoderm microtubule-associated protein-like 4 (EML4), resulting in an EML4-ALK chimeric protein [22].