Aims of this study were to investigate (i) IR isoform composition and IGF-1 receptor expression and (ii) IRS balance in prostate cancer compared to benign tissue as well as to tumor adjacent benign tissue; and (iii) to bring these results in relation to p27Kip1, a well described cell cycle inhibitor in prostate cancer [17]. This evidence concerns the gene IARS1 and prostate carcinoma.