ALK and anaplastic large cell lymphoma: In ALK+ ALCL, NPM–ALK is highly expressed as a result of a high copy number of the NPM promoter and constitutively activates NPM–ALK and downstream signaling including signal transducer and activator of transcription (STAT)3, phospholipase (PLC)γ, phosphatidylinositol 3-kinase (PI3K)–protein kinase B (AKT), and mitogen-activated protein kinase (MAPK)–extracellular signal-regulated kinase (ERK) pathways that are important for cell survival and proliferation, metabolic transformation, and immune evasion via the oligomerization of NPM (10).