CREB1 and COVID-19: Further analyses on this module revealed an enrichment in transcription factor binding sites (CEBP, PU.1, ISL1 and CREB), which are known to positively regulate the levels of cytokines26,36,37 related with COVID-19 severity4 such as, IL-6, IL-1α, IL-1β, IL-12 and other pro-inflammatory cytokines containing a cAMP-responsive elements38 (Fig. 3d).