Effect of IFN-γ and DFO on ST4 cell growth in SCID mice. Anti–asialo GM1–treated SCID mice were challenged subcutaneously with 5 × 106 ST4 cells. After 2 hours, mice were injected at the site of tumor challenge with 0.4 mL PBS/MSA alone (○ and ▾) or 10 μM DFO (▴ and ▪). This treatment was repeated daily for 5 days. At day 7 after inoculum, ST4 cell–treated mice received 0.4 mL PBS/MSA alone (○ and ▴) or 1000 U of IFN-γ (▾ and ▪) daily, for 5 days. Results are indicated (A) as the kinetics of the mean plus or minus SD of the tumor diameter and (B) as percentage of tumor-free mice. Each group consisted of 6 mice except the DFO plus IFN-γ–treated group, which instead consisted of 8 mice.