NFKB1 and infection: While we found that the mRNAs encoding ATF3, CXCL3, and NFKB1 were up-regulated upon rSARS-CoV-2 Nsp1WT infection but were retained inside the nucleus, cells infected with rSARS-CoV-2 Nsp1D33K/E36K/E37K/E41K showed nuclear export of these messages, indicating reversal of mRNA export inhibition by these mutations (Fig. 6 A–C and SI Appendix, Fig. S3).