CD40, a TNFR (Tumor Necrosis Factor Receptor) family member, conveys signals regulating diverse cellular responses, ranging from proliferation and differentiation to growth suppression and cell death. First identified and functionally characterized on B-Cells, CD40 is expressed on a plethora of different cell types, including B-Cells, macrophages, dendritic cells, endothelial cells, and fibroblasts, and this widespread expression accounts for the central role of CD40 in the regulation of immune response and host defense (Ref.1). Binding of CD40 with its counter receptor, CD154 (also termed CD40L [CD40 ligand] or GP39), act...