Eggmanone is a potent and selective PDE4D3 inhibitor with IC50 value of 72 nM that antagonizes the Hedgehog signaling pathway [1].

Hedgehog (Hh) signaling plays an important role in vertebrate development, and its dysregulation is a driver of numerous malignancies. Phosphodiesterase 4 (PDE4) is a target for Hh inhibition. Eggmanone exerts its Hh-inhibitory effects through selective antagonism of PDE4, leading to protein kinase A activation and subsequent Hh blockade [1].

Eggmanone is a potent and selective PDE4 inhibitor that antagonizes the Hedgehog signaling pathway. In Sufu-/- mouse embryonic fibroblasts (MEFs), Eggmanone significantly reduced transcription levels of Gli1 and Ptc1. Eggmanone functioned upstream of Gli processing and nuclear translocation to exert its Hh-inhibitory effects. Eggmanone exhibited potent antagonism of PDE4D3 with IC50 value of 0.072 μM, approximately 40- to 50-fold selective over PDE3A, PDE10A2, and PDE11A4 (IC50s = 3, 3.05, and 4.08 μM, respectively). In Shh-Light2 cells transfected with PDE4D3, Eggmanone restored the increased Hh signaling [1].

Reference:
[1].  Williams CH, Hempel JE, Hao J, et al. An in vivo chemical genetic screen identifies phosphodiesterase 4 as a pharmacological target for hedgehog signaling inhibition. Cell Rep. 2015 Apr 7;11(1):43-50.