IGF1 and myeloid sarcoma: In animal models of MS, an astrocytic IGF upregulation in demyelinating lesions was found (Hinks & Franklin, 1999) and in the absence of IGF signaling remyelination does not adequately occur as OPCs do not proliferate or survive (Mason, Xuan, Dragatsis, Efstratiadis, & Goldman, 2003).