Transforming growth factor-β (TGF-β) belongs to a group of newly discovered superfamily TGF-β regulating cell growth and differentiation. It can combine with the corresponding receptors on the cell surface to change the phenotype of normal fibroblasts, that is, under the condition that epidermal growth factor (EGF) exists at the same time, it can change the adherent growth characteristics of fibroblasts to obtain the ability to grow in agar, and lose the density-dependent inhibition of growth.