Transforming growth factor‐β (TGF‐β) signaling plays a key role tissue homeostasis, which is accomplished through dynamic regulation of many cellular processes, including cell growth and differentiation. The secreted TGF‐β family of ligands binds to homo/heterodimeric cell surface receptors, which triggers the phosphorylation of cytoplasmic SMAD signaling molecules and their translocation to the nucleus to initiate target gene expression. Secreted TGF‐B ligands can be divided into two classes: TGF‐β ‐like ligands that signal through SMADs 2/3 and BMPs that signal through SMADs 1/5. Recent evidence demonstrated that simultaneous synthetic suppression of these two classes of ligands results in expansion of basal cell populations from epithelial tissues from all three germ layers...