OX40L(TNFSF4;CD252) is a cytokine that belongs to the tumor necrosis factor (TNF) ligand family. This cytokine is a ligand for receptor TNFRSF4/OX4. It is found to be involved in T cell antigen-presenting cell (APC) interactions. In surface Ig- and CD40-stimulated B cells, this cytokine along with CD70 has been shown to provide CD28-independent costimulatory signals to T cells.

This protein and its receptor are reported to directly mediate adhesion of activated T cells to vascular endothelial cells. The RefSeq transcript and protein were derived from genomic sequence to make the sequence consistent with the reference genome assembly. The genomic coordinates used for the transcript record were based on alignments.