ATF4 and viral infectious disease: ATF4, a member of the ATF/CREB family of transcription factors, is induced, primarily by mRNA translation, under various stress conditions such as amino acid starvation, endoplasmic reticulum stress, hypoxia, and viral infection; ATF4 then translocates into the nucleus and regulates the transcription of genes that cope with these stress conditions (Pakos-Zebrucka et al., 2016).