ALK and anaplastic large cell lymphoma: NPM-ALK fusion protein is constitutively activated in ALCL, and after its dimerization it activates various signaling pathways, including phosphatidylinositol-3-kinase(PI3K)/AKT/mTOR, JAK/signal transducer and activator of transcription 3 (STAT3), RAS/ERK, and phospholipase C (PLCγ) [12,13,14].