But even this apparently benign role may have a darker side as substance P immunoreactive astrocytes have been identified in MS plaques (Kostyk et al., 1989), and a requirement for substance P/NK-1R interactions has been reported for the maintenance of chronic inflammation in experimental autoimmune encephalomyelitis (EAE) mouse models of MS (Reinke et al., 2006). The gene discussed is TACR1; the disease is myeloid sarcoma.