Volume of B16 tumors. B16 cells were transduced with either pCLPG (black bars) or pCLPGp19 (gray bars) and then treated with 25 ng/ml doxorubicin (Dox) or 10 μM nutlin-3, as indicated, before subcutaneous injection of 1 × 106 cells in C57BL/6 mice (n = 4/condition). After 15 days, the animals were sacrificed, tumors removed and measured. Tumor volume was determined using the formula V = π/6 × D1 × D2 × D3 (where D is the dimension in mm). Presented is the mean and standard deviation of the observed tumor volumes.