Biological effects of transforming growth factors

Transforming growth factors (TGFs) were originally defined by their biological effects on fibroblastic cells (for review see Goustin et al. 1986). These effects included induction of morphological transformation in monolayer culture and Stimulation of colony formation in soft agar. While the early studies with TGFα were somewhat misleading with respect to the function of these factors, they did lead to the purification and cloning of two important growth-regulatory molecules, TGFα and TGFβ. Interestingly, one of these factors (TGFα) is a potent mitogen for a wide variety of cell types, while the other (TGFβ) is the most potent growth-inhibitory Polypeptide known for most cell types (Goustin et al. 1986).