TPB15 is an orally active and potent Hh ( Hedgehog ) signaling inhibitor. TPB15 markedly induces cell cycle arrest and apoptosis in MDA-MB-468 cells. TPB15 blocks Smo (Smoothened) translocation into the cilia and reduced Smo protein and mRNA expression. TPB15 inhibits the expression of the downstream regulatory factor glioma-associated oncogene 1 ( Gli1 ). TPB15 shows good anti-tumor activity with low toxicity.