NPM1 and cancer: ‘ALK fusion proteins’ set members include EML4(1–496)-ALK(1058–1620), NPM1(1–117)-ALK(1058–1620) (48, 49) and others (48, 50, 51), which undergo ligand-independent dimerization, as described in the disease reaction ‘Ligand-independent dimerization of ALK fusions’, belonging to the disease pathway ‘Signaling by ALK in cancer’, meeting the PS3 criterion.