Notes: Supinoxin is an inhibitor of Y593-phosphorylated DEAD-box helicase 5 (DDX5).{67366} It binds to Y593-phosphorylated DDX5 (Kd = ~19 nM), but does not interact with unphosphorylated DDX5, and selectively inhibits β-catenin-dependent ATPase activity over RNA-dependent ATPase activity at 0.2 µM. Supinoxin induces apoptosis in MDA-MB-231 cells (IC50 = 12 nM) and inhibits cell growth in SK-MEL-28 cells (IC50 = 20 nM).