<h4>Objectives</h4>To investigate which phosphodiesterase (PDE) isoforms are expressed in fibroblasts isolated from the tunica albuginea (TA) of patients with Peyronie's disease (PD), and to measure the potency of PDE inhibitors in preventing transformation of these fibroblasts to profibrotic myofibroblasts.<h4>Materials and methods</h4>Fibroblasts isolated from the TA of men undergoing surgery for correction of PD curvature were transformed to myofibroblasts using transforming growth factor beta-1. The gene discussed is TGFB1; the disease is Penile Fibromatosis.