Transforming growth factor-β in breast cancer: too much, too late

The contribution of transforming growth factor (TGF)beta to breast cancer has been studied from a myriad perspectives since seminal studies more than two decades ago. Although the action of TGF beta as a canonical tumor suppressor in breast is without a doubt, there is compelling evidence that TGF beta is frequently subverted in a malignant plexus that drives breast cancer. New knowledge that TGF beta regulates the DNA damage response, which underlies cancer therapy, reveals another facet of TGF beta biology that impedes cancer control. Too much TGF beta, too late in cancer progression is the fundamental motivation for pharmaceutical inhibition.