Inducible nitric oxide synthase (iNOS) expression and nitrotyrosine residues are found in active MS lesions and the active edge of chronic MS lesions (Bo et al., 1994; Cross et al., 1996; Oleszak et al., 1998; Lu et al., 2000; Liu et al., 2001; Marik et al., 2007). This evidence concerns the gene NOS2 and myeloid sarcoma.