To study the effect of pSico-Rac1 on tumor growth, wild-type/Tie1-Cre+ and β3-null/Tie1-Cre+ mice were injected subcutaneously with murine B16F0 melanoma cells and pSico-Con, pSico-Rac1 or pSico-Flk-1 lentiviral suspensions injected intratumorally on days 5 and 10 after tumor cell inoculation. This evidence concerns the gene RAC1 and neoplasm.