Although there is growing evidence suggesting that PPARγ is a master regulator of microglial M2 polarization in immune disease, such as multiple sclerosis (MS) and experimental allergic encephalomyelitis (EAE; Kaiser et al., 2009; Orihuela, McPherson & Harry, 2016; Xu & Paul, 2007), the precise mechanisms remain unclear. The gene discussed is PPARG; the disease is myeloid sarcoma.