MAPT and Alzheimer disease: Recently, we found that multiple neurodegenerative disease-associated proteins undergo the biophysical process of LLPS, such as Tau protein in Alzheimer’s disease (AD) (Ambadipudi et al., 2017; Wegmann et al., 2018; Kanaan et al., 2020; Wen et al., 2021), α-syn in PD (Hardenberg et al., 2020; Ray et al., 2020), FUS (Patel et al., 2015; Zbinden et al., 2020) and TDP-43 (Conicella et al., 2016; Liu and Fang, 2019) associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), etc. The current focus is mainly on α-syn and phase separation processes in mitophagy.