A human monoclonal antibody produced in transgenic mice that attaches to the transmembrane epidermal growth factor (EGF) receptor. Panitumumab may inhibit autocrine EGF stimulation of tumor cells that express the EGF receptor, thereby inhibiting tumor cell proliferation. orA nutrient in the vitamin B complex that the body needs in small amounts to function and stay healthy. Pantothenic acid helps some enzymes use foods and make many substances used in the body and protects cells against damage from peroxides. It is found in almost all plant and animal foods. Pantothenic acid is water-soluble (can dissolve in water) and must be taken in every day. Also called vitamin B5.