Considering that cAMP is one of the important second messengers regulating and mediating a number of cellular responses to extracellular signals, such as hormones, light, and neurotransmitters [59-61], the down-regulated PDE4B mRNA in the PPROM group might imply that the cAMP-related signal transduction was involved in the formation of PPROM. The gene discussed is PDE4B; the disease is preterm premature rupture of the membranes.