ALK5-IN-31 (compound Ex-08) is a selective ALK-5 inhibitor ( IC 50 ≤10 nM), inhibits TGF-β -induced SMAD signaling. ALK5-IN-31 has the potential to inhibit growth of tumour in vivo. ALK5-IN-31 can be used in study of proliferative diseases such as cancer , fibrotic diseases, and systemic sclerosis.