RIPK1 and myeloid sarcoma: The level of tumor necrosis factor alpha (TNFα), the ligand for necroptosis, is elevated in the serum, brain and cerebral spinal fluid of MS patients, and the hallmark mediators of necroptosis including receptor interacting serine/threonine protein kinase 1 (RIPK1) are activated in both mature oligodendrocytes [8] and neurons [9] within demyelinated lesion of both animal models and MS patients.