EML4 and non-small cell lung carcinoma: Anaplastic lymphoma kinase (ALK) fusion, an important oncogenic mutation, occurs in 3% to 7% of non-small cell lung cancers (NSCLC), and EML4 is the most common partner gene.[1] With the widespread application of next-generation sequencing (NGS), more gene breakpoint fusions have been discovered, and functional fusion transcripts can bring targeted clinical benefits.[2] Clinical trials have shown that patients with NSCLC with ALK fusion can obtain significant survival benefits through ALK tyrosine kinase inhibitor (ALK-TKI) treatment.