Buformin (0-10 mM; 5 days) inhibits SKBR3 and BT474 cells growth as a concentration-dependent manner, exhibits IC ₅₀ values of 246.7 μM and  98.6 μM for erbB-2-overexpressing SKBR3 and BT474 cells, respectively.Buformin (0-3 mM; 48 hours)  increases the percentage of cells in G0/G1 phase and reduced the percentage of cells in S phase, especially in the SKBR3 cells.Buformin (0-3 mM; 24 hours) suppresses RTK activation, including erbB-2 and IGF1R signaling  downstream, and Akt activation/phosphorylation is inhibited in both SKBR3 and BT474 cells.

Buformin (oral administation; 7.6 mmol/kg of chow; 7 days) exhibits significantly reduced tumor volumes and weights, and hinders mammary morphogenesis and proliferation in MMTV-erbB-2 transgenic mice