NOTCH1 and extranodal nasal NK/T cell lymphoma: Currently, there are studies showing that the oncogenesis of extranodal NKTCL is closely related to signaling pathways such as NF‐κB, JAK‐STAT, platelet derived growth factor (PDGF), and NOTCH‐1, among which, NF‐κB and JAK/STAT are the best studied in NKTCL.