ATF4 and microcephaly: ZIKV triggers ER stress and UPR both in human cortices in vivo and in human neural stem cells ex vivo and contributes to the development of microcephaly in mice, mainly through over-activation the PERK-eIF2α-ATF4 pathway, which (as seen in the Elp3 knock out model) results in an impairment of indirect neurogenesis [76].