RAC1 and neuroblastoma: To further confirm that altered activated Rho GTPases played a critical role in metformin-induced cell death, we infected neuroblastoma cells with adenoviruses expressing either GFP-fused constitutively active or dominant negative forms of RhoA, Rac1 and Cdc42, and treated with metformin (10 mM) for 4 days (SK-N-BE(2)) or 6 days (SH-SY5Y).