It is worth noting here that although both Drosophila and mouse models of adRP describe a protective role for Perk in retinal degeneration (Athanasiou et al., 2017; Chiang et al., 2012; Vasudevan et al., 2020), there has been conflicting evidence on the role of ATF4 in the mouse adRP model (Bhootada et al., 2016). This evidence concerns the gene PLIN2 and retinal degeneration.