Mechanistic interrelationships between two superfamilies: the steroid/retinoid receptors and transforming growth factor-beta.

The fields of endocrinology and peptide growth factors can no longer be studied independently, nor can hypotheses about the modes of action of hormones and growth factors be constrained by outmoded classic definitions. Although much is still to be learned about the mechanisms of induction of TGF-beta activity by steroids/retinoids, about the involvement of specific nuclear receptors and about the factors regulating the differential effects of steroids/retinoids on the various isoforms of TGF-beta, it is clear that the identification of the interrelationships between these two superfamilies of multi-functional effectors has heralded a new era of discovery of the underlying regulatory events controlling cellular proliferation and differentiation.