Second, the combinations of cytokines mentioned in this study, as well as other cytokines that are highly expressed in the degeneration of dopamine neurons or in PD patients (e.g., IL1α, IL2, IL1β, TNFα, TGF‐β, and IFNγ [48]), require further investigation to validate their potential safety in grafted mDA cells. Here, TGFB1 is linked to Parkinson disease.