KARS1 and vitamin A deficiency: Indeed, aminoacyl-tRNA synthetases are induced downstream of the PERK branch of the unfolded protein response [77,78], and we identified four aminoacyl-tRNA synthetase genes (GluProRS, IleRS, LeuRS, and LysRS) [2] and seven aminoacyl-tRNA synthetases (LeuRS, LysRS, MetRS, ThrRS, HisRS, IleRS, ValRS) that showed increased expression levels in response to vitamin A deficiency (Figure 4A).