OX40 is a T-Cell activator that is believed to promote the survival (and perhaps prolong the immune response) of CD4+ T cells at sites of inflammation. The co-stimulatory molecule OX40L (OX40 Ligand), a member of the TNF (Tumor Necrosis Factor) super family, is a 32 kDa protein, which has a 183 aa residue glycosylated polypeptide that consists of a 21 aa residue cytoplasmic domain, a 23 aa residue transmembrane segment, and a 139 aa residue extracellular region. OX40 has been shown to be important in T-Cell priming and cytokine production. OX40 has limited expression and is not constitutively present on naive T cells, only peaks in expression 3–4 days after the initial activating signal, and is rapidly and highly re-expressed [...]