It can therefore be concluded that the inhibition of growth of CP70 ovarian cancer cells in vivo by metformin occurs via the inhibition of MRP2 expression, which was clearly seen at mRNA level with significant decreases at 0.1, 1 and 10 mM metformin, but less obvious at protein level because it was only significant at 10 mM metformin. This evidence concerns the gene ABCC2 and ovarian carcinoma.