EML4-ALK fusion gene can improve the expression of anaplastic lymphoma kinase (ALK) protein and activate ALK inducing tumor cells proliferation and anti-apoptosis.EMLA-ALK fusion gene in nonsmall-cell lung cancer which has unique clinical and pathological features is more common in young femal,never smokers,and adenocarcinoma patients,At present,EML4-ALK fusion gene can be detected using RT-PCR,FISH and IHC.Crizotinib,an ALK inhibitor,can block the gene's signal pathway and restrain tumor's activity.