CLIC1 and cancer: In fact, although several of the previously reported effects of metformin in cancer cells could be reconciled with the cell cycle regulation induced by CLIC1 inhibition (i.e. modulation of kinase systems that control proliferation and/or survival [17, 22, 24], or the activation of transcription factors [26, 27]), recent data also reported a direct effect of this drug on complex I and oxidative phosphorylation, which, besides being responsible for its metabolic effects, could also interfere with cell proliferation [54, 57].