In fact, IL-8 expression could simultaneously be regulated by multiple transcriptional factors and, in a model of chronic infection during cystic fibrosis, a non-producing ExoU P. aeruginosa strain stimulated IL-8 secretion through a complex mechanism that included activation of NF-κB, AP-1, NF-IL6, CHOP and CREB [16]. This evidence concerns the gene CREB1 and cystic fibrosis.