CD40 and renal cell carcinoma: In light of its ability to up-regulate CD40 (Fig. 1c), we examined whether IFN-γ could augment soluble agonist (or mCD40L)-mediated effects; IFN-γ could not sensitise RCC cells to G28-5 mAb, although it caused some enhancement in mCD40L-mediated death (Fig. 2d).