ADSL and digestive system infectious disorder: Recombinant RegIIIγ and HIP/PAP proteins prevent lethal Citrobacter colitis.[40] Moreover, genetic deletion of RegIIIγ increases susceptibility to intestinal infection by Salmonella enteritidis, a Gram-negative bacterium.[14] Thus, while it is unlikely that RegIIIγ or HIP/PAP exhibit direct microbicidal activity, it remains conceivable that they may work cooperatively with other AMPs or host immune cells to serve an antimicrobial function in certain Gram-negative infections.