The activity of cytosolic phospholipase A2 (cPLA2) may be altered by calcium or by phosphorylation of serines in the cPLA2 molecule. Activation of TLR4 receptors or surface receptors by sphingosine 1 phosphate may signal for phosphorylation of cPLA2. Using this system, a member of the S-100 family of proteins (p11) was identified as interacting with cPLA2. The promoter region of the p11 gene has been cloned and characterized. Recombinant cPLA2 has been produced in bacteria and in insect epithelial cells. Treatment of these proteins with thiol modifiers reduces activity. Treatment with S-nitroso-glutathione also alters activity. Ongoing studies include production of recombinant protein and modulation of enzyme function by recombinant proteins which bind bind to cPLA2.