IGF1 and benign prostatic hyperplasia: Previous studies have focused on the use of in vitro primary cell cultures in order to characterize the expression of IGF-I separately in each cellular compartment of the prostate; the initial findings suggested that prostatic epithelial cells, whether from normal, benign prostatic hyperplasia, or malignant tissues, do not synthesize or secrete significant amounts of IGF-I (Peehl et al., 1996).