P4HB and microcephaly: In vitro and in vivo studies have shown an increase in ER stress proteins as well as expression of key molecules of the UPR, such as glucose regulatory protein 78 (GRP78), calreticulin, calnexin, and protein disulfide isomerase (PDI) in infected neural cells (Ropidi et al., 2020), resulting in neurogenesis inhibition and microcephaly (Gladwyn-Ng et al., 2018; Figure 3).