CD40 and hepatocellular carcinoma: As murine hepatoma cells Hepa129-mAFP and Hepa1–6 express small amounts of CD40 (about 10–30% of cells, not shown), apoptosis may also be mediated by direct CD40/CD40L interaction between soluble CD40L secreted in the supernatant of Ad-CD40L-DC and CD40 from tumor cells.