Tags: Protein.
CD134 also known as OX40 is a member of the TNFR-superfamily of receptors which is not constitutively expressed on resting naïve T cells unlike CD28. OX40 is a secondary costimulatory molecule expressed after 24 to 72 hours following activation; its ligand OX40L is also not expressed on resting antigen presenting cells but is following their activation.