It is conceivable that the failure of remyelination observed in the majority of chronic MS patients may be multifactorial and due to: (a) a local paucity of ODC lineage precursors, and/or (b) a local excess of OPCs with a fate of apoptotic death, and/or (c) a local deficiency in the neurotrophic growth factors (e.g., EGF) and other molecules (e.g., PrPcs and Cbl) essential for the normal OPC differentiation and ODC myelination, and/or (d) differentiation block of OPCs, and/or (e) an increased presence of myelination inhibitors. Here, EGF is linked to myeloid sarcoma.