Specific cytotoxic T lymphcyte activities in test mice treated with different immunization regimes. (a) Schema for gene-based vaccination and adjuvant treatment against test tumors in mouse model. One primer and two boosters were performed on days 0, 7 and 14. Mouse immunization sites were either pre-treated with shikonin (100 μg/site/mice) or transfected with pRANTES vector 24 hours before each primer and booster. The empty vector or vehicle control alone was used as a corresponding control. One week after the last booster, CTL activities from splenocytes (b) and lymph node cells (c) were determined from immunized mice. Target tumor cells (B16/hgp100) were co-cultured with effector cells at indicated ratios of effector:target (E:T) cells from 5:1 to 80:1 and assayed for CTL activity. *, P < 0.05, versus pVector or vehicle controls. (Seven mice per group).