Role of cellular and humoral immunities in DKK1-DNA vaccine–induced antitumor response. Mice (5 per group) were vaccinated thrice with DKK1-DNA vaccine plus CpG, followed by in vivo depletion of CD4⁺ or CD8⁺ T cells, or NK cells, or B cells and then tumor challenge. Tumor burdens were measured twice each week. Mice were euthanized when subcutaneous tumors reached 225 mm² or when mice became moribund. Shown are tumor burdens (A) and survival (B) of mice receiving different treatments. (C) Titers of DKK1-specific Abs in mice receiving different treatment, and (D) tumor burdens of DKK1-DNA plus CpG-vaccinated mice treated with IgG or CD20 mAb to deplete B cells. Representative results of 1 of 2 independent experiments performed are shown. *P < .05; **P < .01, compared with controls.