rPLA2 is a calcium-dependent cytosolic phospholipase A2 (cPLA2) initially isolated and characterized from bovine and human red blood cells (RBCs). It has a molecular mass of 42 kDa and biochemical properties similar to cPLA2 Type IV. EA4 is a quinone derivative that inhibits rPLA2 with a Ki of 130 μM. It inhibits the ionophore-induced arachidonic acid release from human and bovine red blood cells (RBCs), indicating that rPLA2 is responsible for the Ca2+-dependent release of arachidonic acid from mammalian RBCs. EA4 causes significant time- and concentration-dependent induction of cytochrome P450 1A1 (CYP1A1) mRNA and protein in murine hepatoma Hepa-1c1c7 cells. EA4 also modulates CYP1A1 and CYP1B1 expression in other cell lines such as MCF-7, Hep-G2, and HL-60.
