IGF1 and benign prostatic hyperplasia: Other genes of interest added “manually” for RT-PCR analysis were IGF1, IGF1R, TGFB1, TGFB3, TGFBR1, and TGFBR2. The expression levels of these target genes were measured in RNA pools prepared from TZ tissues designated as having mild, moderate, and severe BPH changes, as well as moderately and poorly differentiated prostate cancer.