In PD cell models, conditioned medium from FGF21-overexpressing MSCs or recombinant FGF21 reversed dopaminergic neuron death, reduced mitochondrial ROS, and enhanced the levels of phospho-Akt, mature BDNF, and Bcl-2, underscoring the therapeutic potential of FGF21-based MSC treatments for PD [133]. Here, BCL2 is linked to Parkinson disease.