Cell-permeable. A TGF-β type I receptor (ALK5) inhibitor. Inhibits ALK5 autophosphorylation (IC50 = 4 nM). Can replace one of the four reprogramming factors Sox-2. RepSox has been successfully used in the direct reprogramming of mouse fibroblasts through induction of Nanog transcription. MW: 287.32. Purity ≥98% by HPLC