All three agonist antibodies are necessary in combination with IL-2 for optimal anti-tumor effects. Following intrakidney injection of Renca cells, mice received the treatments listed as indicated by arrows. Some mice received the complete treatment of Tri-mAb + IL-2, whereas other groups received various pairs of antibodies as listed either alone or in combination with IL-2. Some mice received no treatment to act as controls. Numbers in parentheses depict number of mice per group. Results from a single experiment, P < 0.05 for three antibodies + IL-2 vs two antibodies + IL-2 (Log-rank test), except for the comparison between Tri-mAb + IL-2 and MD5.1/CD40 + IL-2 which tended towards significance at P = 0.079.