UBE3A and autism: Xu et al. (2018) also identified impaired RA homeostasis as a key mechanism underlying the UBE3A hyperactivity-induced autism model. In their autism model, RA reduction decreased the binding to RARα and elevated the binding of RARα to GluA1 mRNA without impairing the RARα level, which reduced GluA1 translation and HSP (Poon and Chen, 2008; Xu et al., 2018). In our study, the increase in HSP might be due to the downregulation of RARα, which reduced the binding of RARα to GluA1 mRNA and thus increased GluA1 translation (Poon and Chen, 2008; Hsu et al., 2019).