AZ12601011 is an orally activesubtype-selective TGF-β type I receptors active site inhibitor (active-site affinity: ALK4/5/6 Kd = 2.6/2.9/42 nMALK1/2/3 Kd = 40/15/40 μM) th at prevents ALK4/5/7-mediated Smad2but not ALK1/2/3/6-mediated Smad1phosphorylation (10 μM; NIH3T3 expressing respective constitutively active receptors). AZ12601011 inhibits 4T1 murine mammary carcinoma growth in cultures (IC50 = 400 nM) and in vivo (50 mg/kg bid. po. mice). AZ12601011 also causes heart valve lesions and physeal dysplasia in rats (150 mg/kg/day po. for 7 days)consistent with a critical role of ALK5 in maintaining the integrity of heart valve and physis.
