Consistent with a previous study,[8] IL‐3 was colocalized with glial fibrillary acidic protein (GFAP), a marker of astrocytes, and IL‐3Rα was colocalized with ionized calcium binding adaptor molecule 1 (Iba1), a marker of microglia in the substantia nigra pars compacta (SNpc) of A53T PD mice (Figure 1D,E), suggesting that astrocytes are the source of IL‐3 and that microglia express IL‐3Rα. The gene discussed is GFAP; the disease is Parkinson disease.