RAC1 and neoplasm: Results also showed that although pSico-Flk-1 treatment reduced significantly B16F0 melanoma size (P<0.05) in both genotypes, when compared with pSico-Con controls, pSico-Rac1-treatment did not affect tumor size in wild-type/Tie1-Cre+ mice, but significantly reduced tumor size in β3-null/Tie1-Cre+ mice (Figure 3A).