Mouse CCL19 (MIP-3 beta) Recombinant Protein. Macrophage Inflammatory Protein-3 beta (MIP-3 beta), also called CCL19, is a chemokine that is expressed in the thymus, lymph nodes and activated bone marrow stromal cells. MIP-3 beta signals through the G protein-coupled receptor, CCR7, to regulate normal lymphocyte recirculation and homing of T and B cells to the lymph nodes. Human MIP-3 beta shows activity on mouse cells.