TP53 and infection: Pertinent to these possibilities, analyses of bulk RNAseq data revealed 1) an increase in basal cell and cell cycling genes (e.g., TP53 cell cycle pathway) in the interval post-peak infection, consistent with the notion that at least part of the mucus cell metaplasia represented a cell proliferative/replacement response to viral injury (Figure 6B); and 2) strong upregulation of EGFR signaling pathways that are likely to mediate a component of the mucus metaplastic response to SARS-CoV-2 (46, 48, 49) (Figure 6C).