Inhibition of Rac1 blocks vGPCR tumorigenesis. (A) Western blot demonstrating expression of RacN17 or PAKN in immortalized endothelial cells (SVECs) stably expressing bicistronic constructs (EC-vGPCR-I-GFP, EC-vGPCR-I-PAKN, or EC-vGPCR-I-RacN17). (B) EC-vGPCR-I-PAKN and EC-vGPCR-I-RacN17 show reduced secretion of cytokines with respect to EC-vGPCR-I-GFP. (C) EC-vGPCR-I-GFP, EC-vGPCR-I-PAKN, or EC-vGPCR-I-RacN17 was used to generate tumors in 8-week-old athymic nu/nu mice. Mice were killed after 8 weeks. Tumors formed from EC-vGPCR-I-GFP were significantly larger than those formed from EC-vGPCR-I-PAKN or EC-vGPCR-I-RacN17. Data represent the mean ± SEM of 10 tumors from a typical experiment. Average tumor weight is indicated.