Inhibins and activins are involved in regulating a number of functions such as hypothalamic and pituitary hormone secretion, gonadal hormone secretion, germ cell development and maturation, erythroid differentiation, insulin secretion, nerve cell survival, embryonic axial development or bone growth depending on their subunit composition. Activins oppose the funtions of inhibins. Inhibins are predominantly expressed in liver, uterus and ovary tissue, but also in benign prostatic hyperplasia. Inhibin A, a dimer of (alpha) and (beta)-A, and inhibin B, a dimer of (alpha) and (beta)-B, have been shown to inhibit the secretion of follicle stimulating hormone. Inhibin (beta)-C forms a homodimer and its expression is predominant in adult liver and in benign prostatic hyperplasia.