AR-9281 is primarily used in research settings as a potent and selective inhibitor of the ALK5 (TGF-β type I receptor) kinase. It plays a key role in studies related to fibrosis, where it helps suppress TGF-β signaling—a major pathway involved in tissue scarring and extracellular matrix accumulation. Due to its ability to modulate this pathway, AR-9281 is employed in preclinical models of diseases such as liver fibrosis, kidney fibrosis, and pulmonary fibrosis to evaluate therapeutic potential.

It is also utilized in cancer research, particularly in tumor microenvironment studies, where TGF-β signaling contributes to immune evasion and metastasis. By inhibiting ALK5, AR-9281 helps restore immune surveillance and reduce tumor progression in experimental models. Its selectivity makes it a valuable tool for dissecting TGF-β-dependent mechanisms without significant off-target effects.

Additionally, AR-9281 has been used in stem cell and developmental biology research to control differentiation processes influenced by TGF-β, such as epithelial-to-mesenchymal transition (EMT). Overall, its main application lies in pharmacological and mechanistic studies targeting fibrotic diseases and cancer.