Because bacterial infection is the most frequent cause of preterm birth, we also examined whether the bacterial product lipopolysaccharide (LPS) and serum amyloid A1 (SAA1), an acute-phase protein produced in large amounts following infection (34), were capable of modulating the effects of BK and DABK on PTGS2 expression in human amnion fibroblasts. Here, PTGS2 is linked to infection.