Growth rates of PSC-containing and PSC-free DSL-6A/C1 tumors in nude mice and effects of IFNγ. Injections of tumor cells, alone or together with PSC, was performed as described in the "Methods" section. Treatment with IFNγ (10 μg per day for 4 weeks, n = 4) started when the faster-growing tumor had reached a size of 6 mm in one dimension (day 0). Initiation of IFNγ treatment is indicated by the symbol (+). Control animals (n = 6) received solvent injections only. Indicated are the average values of the tumor volumes ± SEM. * p < 0.05 vs. without PSC (paired t-test), # p < 0.05 vs. untreated (unpaired t-test).