Although the findings from Oda et al. in HCT-9, Calu-3, and Vero-3 indicated the activation of the UPR and IRE1a pathway, they contradict previous reports as they found in samples from patients with severe COVID-19 the overexpression of both activated IRE1a and XBP1s, thus indicating the RNase activity of IRE1 [98]. Here, ERN1 is linked to COVID-19.