Studies in highly active demyelination cases including acute MS lesions and neuromyelitis optica (NMO) showed that immunoreactivity for Cx43 was completely lost in highly degenerative GFAP positive astrocytes within the active lesion, while Cx43 was up-regulated in chronic lesions [110], reflecting the acute and chronic EAE findings (above). This evidence concerns the gene GJA1 and myeloid sarcoma.