Some of the most differentially expressed genes in humans compared to in vitro were virulence factors, the majority of which had increased expression in CF sputum, and included gamma-hemolysin (hlgABC), superantigen-like proteins (ssl1, ssl2, ssl3, ssl5, ssl9, ssl10, ssl12, ssl13, and ssl14), leukocidins (lukG), extracellular matrix binding proteins (emp, scc, and fnbA), and exopolysaccharide (icaABC). This evidence concerns the gene SERPINB3 and cystic fibrosis.