The role of single proteins such as aquaporin-1 in the transport of water across the peritoneal membrane (Yang et al., 1999; Ni et al., 2006) or NOS (Nitric oxide synthase) isoforms in peritonitis (Ni et al., 2010), as well as, IL-6 in inflammation (Hurst et al., 2001; McLoughlin et al., 2004) and TGF-β in encapsulating peritonitis (Park et al., 2008) were explored using genetically modified mice. Here, AQP1 is linked to peritonitis.