Figure 4: SKP-SC-CM regulates 6-OHDA-induced autophagy by upregulating the PI3K/AKT/mTOR pathway in SH-SY5Y cells. SH-SY5Y cells were pretreated with SKP-SC-CM, RAPA, or 3-MA for 4 hours and then treated with 6-OHDA (50 μM) for 12 hours. (A–C) Bands of p-AKT/AKT, p-PI3K/PI3K, and p-mTOR/mTOR. (D–F) Quantitative results of the protein expression. All data are presented as the mean ± SEM, normalized to the control group. The experiments were repeated five times. *P < 0.05, **P < 0.01, ***P < 0.001 (one-way analysis of variance followed by Tukey’s post hoc test). 3-MA: 3-Methyladenine; 6-OHDA: 6-hydroxydopamine; AKT: Protein kinase B; Con-CM: control conditioned medium; mTOR: mammalian target of rapamycin; p-AKT: phosphorylated protein kinase B; PI3K: phosphatidylinositol 3 kinase; p-mTOR: phosphorylated mammalian target of rapamycin; p-PI3K: phosphorylated phosphatidylinositol 3 kinase; RAPA: rapamycin (autophagy activator); SKP-SC-CM: skin-derived precursor-Schwann cells conditioned medium.