Background:

SANT-2 is a Smoothened (Smo) receptor antagonist.[1],[2] It binds to the Smo receptor (Kd = 12 nM) and inhibits binding of the Smo receptor agonist SAG-1.3 (SAG; Item No. 11914) and antagonist cyclopamine(Kis = 7.8 and 8.4 nM, respectively). SANT-2 inhibits hedgehog signaling induced by an N-terminal fragment of sonic hedgehog (Shh) in an Shh-LIGHT2 cellular assay (IC50 = 30 nM).[1]

Reference:
[1]. Chen, J.K., Taipale, J., Young, K.E., et al. Small molecule modulation of smoothened activity. Proc. Natl. Acad. Sci. USA 99(22), 14071-14076 (2002).
[2]. Rominger, C.M., Bee, W.L.T., Copeland, R.A., et al. Evidence for allosteric interactions of antagonist binding to the smoothened receptor. J. Pharmacol. Exp. Ther. 329(3), 995-1005 (2009).