It has previously been reported that metformin downregulates the levels of IGF-IR in prostate cancer cells (Malaguarnera et al. 2014, Kato et al. 2015), but we assessed the abundance of IGF-IR by Western blotting and measured the levels of IGF-I and IGF-II by radioimmunoassay, and none of these variables were altered in the DU145 or LNCaP cells in these experiments (data not shown). This evidence concerns the gene IGF1 and prostate cancer.