We show that the F1174S mutation in EML4-ALK positive NSCLC impairs ALK autophosphorylation in all three EML4-ALK variants studied here (V1, V3a and V3b), in contrast to the reported ALK F1174C/L/V mutations, which cause resistance to the ALK inhibitor crizotinib. This evidence concerns the gene ALK and non-small cell lung carcinoma.