Bone Morphogenetic Protein-4 (BMP-4) is an extracellular multifunctional signaling cytokine that is also a member of the TGF-β family. BMP-4 can bind with the TGF-β receptor and trigger SMAD protein signal transduction. BMP-4 has a significant expression in the prostate, it plays a vital role in the development of mesoderm into bones and the development of the epidermis and Dorsal-Ventral axis.