Role of IL-6 trans-signaling in the sporadic AOM-induced tumor model. (A) Schematic representation of the sporadic CRC model. WT or sgp130 transgenic mice were injected i.p. with AOM (10 mg/kg) once a week for a total of 6 wk. The spontaneous formation of distal colonic tumors was monitored by endoscopy once every week after 6 wk of AOM treatment. (B) Representative endoscopy images of distal colonic tumors (arrowhead) from WT or sgp130Fc transgenic mice at 11 wk. Bars, 2 mm at the plane of the head of the endoscope. (C) Representative number of protruding lesions from WT or sgp130Fc transgenic mice scored by endoscopy at 8, 11, and 17 wk. Data presented as mean ± SEM using n ≥ 6 mice per cohort. *, P < 0.05; **, P < 0.01; by Student’s t test. (D) Photomicrographs of representative colons of mice of the indicated genotypes. Tumors are indicated by arrows. Bars, 1 cm. (E) Total tumor burden of WT or sgp130Fc transgenic mice at 20 wk. Data presented as mean ± SEM using n ≥ 8 mice per cohort. *, P < 0.05 by Student’s t test. (F) Representative IHC staining and quantification for pSTAT3, pEGFR, and CD3 from WT and sgp130Fc transgenic mice. Bars, 100 µm. Data presented as mean ± SEM and analyzed by Student’s t test.