While Nrf2 activation in vivo and in vitro can have profound effects on microglia [58,67], and Nrf2 activation can be observed in cultured microglia [58,59,99], direct evidence for Nrf2 activation specifically in microglia in vivo is limited to elevated GPx1 in the cingulate gyrus [41] and HO1 in the substantia nigra of post-mortem human Parkinson’s disease brains [59]. This evidence concerns the gene HMOX1 and Parkinson disease.