Tags: Protein.
CD154 also called CD40 ligand or CD40L is a protein that is primarily expressed on activated T cells and is a member of the TNF superfamily of molecules. It binds to CD40 on antigen-presenting cells (APC) which leads to many effects depending on the target cell type. In general CD40L plays the role of a costimulatory molecule and induces activation in APC in association with T cell receptor stimulation by MHC molecules on the APC.