FNDC5 and Parkinson disease: As a result, Akt inhibitor and ERK inhibitor hindered irisin-induced inhibition of apoptosis in PD models induced by neurotoxins, which was reflected by the expression levels of MMP, Bcl-2, cleavage of casepase 3, and the ratio of Bcl-2/Bax (Fig. 8a–e, f–i).