SLC47A2 and prostate cancer: In contrast and although LnCaP, a prostate cancer line, proved to be particularly sensitive to metformin and in a concentration range that was within that expected clinically and correlated with a high expression of mRNA for OCT3 and low expression of MATE2 for the other cell lines, very high concentrations, up to 10mM, of metformin were required to see significant inhibition, and a strong significant correlation between inhibition of proliferation and MATE2 expression was not seen (254).