Anti-secretory factor (AF) is an endogenous protein which has been characterized in vivo and in vitro. AF is a part of the proteasome and controls the transport of water and ions across the cell membrane. AF plays an important part in the immune system and has an anti-secretory and anti - inflammatory effect in vivo along with complementary substances, primarily c3C. Researchers have chemically characterized and cloned AF's cDNA and shown that the active part (anti-secretory and anti-inflammatory) is located in the amino terminal portion of the protein. The exact mechanisms behind AF's regulatory effect on the secretory / inflammatory progress, however, is largely unknown, but AF is probably involved in the liquid transport mechanisms in the cell pathway.