Although resident cells of the CNS including microglia and endothelial cells express CXCL1 24, 25, astrocytes have been shown to express CXCL1 in EAE as well as in MS lesions 26, 27, 28 and this informed our decision to select astrocytes as our target cell for ectopic expression of CXCL1. The gene discussed is CXCL1; the disease is myeloid sarcoma.