PPARG and brain ischemia: Recombinant human fibroblast growth factor 21 (rhFGF21) has been found to decrease M1-type polarization of microglia after cerebral ischemia, promote M1-to-M2-type polarization transformation, and activate PPARγ in the ischemic penumbra (Jiang et al., 2018; Wang D. et al., 2020).