Here, we report that EML4-ALK-driven tumorigenesis is linked with a stem-like property and that the ALK activity plays a key role in maintaining stem-like properties of EML4-ALK+ NSCLC cells as characterized by increased capability of tumor formation and expression of stemness-associated molecules such as ALDH, NANOG, and OCT4. This evidence concerns the gene EML4 and neoplasm.