Antitumor effects of PEGylated LMB-2s on ATac-4 solid tumor. ATac-4 cells (2 × 106) were inoculated s.c. on day 0 into nude mice. Starting on day 4, mice were treated with i.v. injections of immunotoxins on days 4, 6, and 8. Groups of five mice were treated for each dose QOD × 3 at each dose level. (A) LMB-2. (B) cys1-LMB-2. (C) PEG5k-LMB-2. (D) PEG20k-LMB-2. The following symbols were used: ○, diluent; □, 0.100 mg/kg; ■, 0.050 mg/kg; ▵, 0.025; ▴, 0.013 mg/kg; ♦, 0.006 mg/kg; ●, PEG5k 0.5 mg/kg; ⋄, PEG20k 0.5 mg/kg.