A 83-01 is a potent small molecule inhibitor primarily used in research to block the activity of transforming growth factor-beta (TGF-β) type I receptors, including ALK4, ALK5, and ALK7. It is widely applied in cell culture studies to prevent TGF-β-induced epithelial-to-mesenchymal transition (EMT), making it valuable in stem cell research, particularly in maintaining the pluripotency of induced pluripotent stem cells (iPSCs) and embryonic stem cells during expansion. It is also used to enhance the efficiency of reprogramming somatic cells into iPSCs by suppressing TGF-β signaling, which can act as a barrier to reprogramming. In regenerative medicine, A 83-01 supports the directed differentiation of stem cells by modulating signaling pathways involved in cell fate decisions. Additionally, it has been employed in cancer research to study TGF-β-mediated tumor progression, metastasis, and immune evasion. Due to its ability to inhibit fibrotic pathways, it is explored in models of fibrosis for potential therapeutic development.