Cell-permeable. A potent inhibitor of Sonic hedgehog (Shh) signaling; high affinity antagonist of smoothened activity (Kd = 1.2 nM). Inhibits smoothened agonist effects with an IC₅₀of 20 nM in Shh-LIGHT2 cells. SANT-1 inhibits both wild type and oncogenic Smo with equal potency.