BMP4 and cancer: BMP-4, as a member of the transforming growth factor β family is involved in the development of many organs and tissues and was shown to play a role in cancer progression.24–26 BMP-4 is synthesized as a large inactive precursor which is proteo-lytically cleaved to the mature protein in a multistep process.27 Non-processed BMP-4 is targeted to the lysosomes for degradation which can lead to severe loss of BMP-4 activity in specific tissues.28,29