131I potentiates BTZ treatment efficacy and suppresses stemness in tumor-bearing mice. (A) Growth of CT26 tumors in mice treated with BTZ alone (n = 4) or BTZ plus 131I (n = 4) compared to vehicle-injected animals (n = 3). (B) Growth of CT26/NIS-cODC tumors in mice treated with 131I alone (n = 8), BTZ alone (n = 7) or BTZ plus 131I (n = 8), compared to vehicle-injected animals (n = 7). The weights of mice after tumor removal are also shown. All data are the mean ± SD of tumor volume. †P < 0.005, ‡P < 0.001, compared to vehicle-treated controls. (C) Western blots for CD133 (left) and ALDH3A1 expression (right) in residual CT26/NIS-cODC tumors after treatment with vehicle (n = 7), BTZ (n = 7), or BTZ plus 131I (n = 8). Blots are cropped with single blot parts separated by space. For full length blot pictures, see supplement Fig. 5. Bars are the mean ± SD of % band intensities normalized to β-actin bands. **P < 0.01, †P < 0.005, ‡P < 0.001, compared to vehicle-treated controls. BTZ: bortezomib; ALDH3A1: Aldehyde dehydrogenase 3A1.