NPM1 and anaplastic large cell lymphoma: NPM1-ALK is by far the most common and well described ALK fusion protein detected in patients diagnosed with ALCL (accounting for 70–80% of ALK+ ALCL cases [19]) suggesting either that these two genes are predisposed in some way to translocation events in the precursor cells of ALCL and/or that an NPM1 translocation partner provides a selective advantage to incipient tumour cells over other fusion proteins [3,10,20,21].