ACE and myeloid sarcoma: Based on previous observations demonstrating that serum ACE activity increases significantly after smoking (Kitamura, 1987) and chronic smoking results in enhanced RAS activation in monozygotic twins, discordant for smoking (Laustiola, Lassila, & Nurmi, 1988), Correale and Farez (2015) (Correale & Farez, 2015) recently investigated whether RAS might be involved in immunomodulatory effects of smoking on MS progression.