To test whether inactivation of ARF6 (ARF6-GDP) could produce the same effect, we treated human melanoma cells with SecinH3, an ARF6 guanine exchange factor inhibitor that reduces ARF6-GTP levels11, 36 (Fig. S1g) and reduces spontaneous metastasis of human BRAFV600E melanoma xenograft tumors11. The gene discussed is ARF6; the disease is melanoma.