The ALK receptor tyrosine kinase was initially identified as a member of the insulin receptor subfamily that acquires transforming capability when it is truncated and fused to NPM (nucleophosmin) in a chromosomal rearrangement that is common in anaplastic large cell lymphomas (ALCL) and in non-Hodgkin’s lymphoma with a T cell phenotype (Morris et al. 1994;Wellmann et al. 1995). The gene discussed is ALK; the disease is anaplastic large cell lymphoma.