MTOR and neurodegenerative disease: Wang et al. (2021) found in rotenone-treated PC12 cells in vivo and in vitro studies on PM2.5 and neurodegenerative diseases, exposure to PM2.5 can reduce the LC3II/LC3I ratio and the expression level of Atg5, and increase the mammalian target of rapamycin (mTOR) expression levels, suggesting that PM2.5 exposure inhibited autophagy.