(A) C57BL/6 MIF+/+ mice were injected with B16 cells (s.c.). 7 days post tumor inoculation, mice were treated i.p. with 4-IPP (80 mg/kg in corn oil) or vehicle control (corn oil) for 14 days and tumor volumes were plotted. Data represents the average tumor volumes of 10 mice/group ± SEM and are representative two independent experiments. (B) Tumor growth was monitored daily in all animals until sacrifice due to tumors exceeding 5% of body weight. (C) Resident PECs from C57BL/6 mice bearing a s.c. melanoma tumor (n = 10) were pooled and activated in vitro with LPS and either DMSO (vehicle control) or 4-IPP (50 μM) for 24 hours. mRNA, protein and nitric oxide levels were analyzed from indicated cells. Data represents the average of ± SEM of duplicate samples representative of three independent experiments. P values = *, p≤0.05; **, p≤0.005; ***, p≤0.0005.