The constitutive kinase activity of NPM-ALK and indeed other ALK fusions such as echinoderm microtubule-associated protein-like 4 (EML4-ALK in Non-Small Cell Lung Cancer; NSCLC) is thought to arise from self-dimerisation through N-terminal oligomerisation domains, leading to auto- and transphosphorylation of ALK [41,42]. Here, EML4 is linked to non-small cell lung carcinoma.