CTLA-4•FasL inhibits tumor growth in vivo . (A) Ex vivo JY cells were injected subcutaneously to irradiated NUDE mice. At day 5 after JY injection, tumor volume was calculated and mice were treated daily with subcutaneous injections of CTLA4-FasL (10 μg twice a day for 5 days for one treatment course or 2 μg twice a day for 4 days for four consecutive weeks). Control animals received similar volume of PBS. The results represent the mean +/- SE volume of tumors (n = 10 for each group). * - P <0.05, **P <0.01 between PBS group and treatment group (B) Five days post s.c. injection of human JY tumor cells to irradiated-NUDE mice the mice were treated with 10 ug CTLA4-FasL or PBS twice a day for 5 consecutive days. Tumors were harvested one hour after last injection, fixated and embedded in paraffin, and tissue sections were processed and stained with anti cleaved caspase 3 antibody. (C) 8 days following last CTLA4-FasL (100 μg a day, 4 days), or vehicle injection mice livers were harvested, fixated and embedded in paraffin, and stained with H&E.