PNU-74654 is an inhibitor of Wnt/β-catenin pathway with an IC₅₀ of 129.8 μM in NCI-H295 cell. IC50 & Target: 129.8 μM (Wnt/β-catenin, NCI-H295 cell)^[1] In Vitro: PNU-74654 binds to β-catenin with a K_D of 450 nM. The Tcf3/Tcf4-binding surface on β-catenin contains a well-defined hot spot around residues K435 and R469. The binding mode of PNU-74654 involves the two narrow pockets on either side of this hot spot^[2]. In NCI-H295 cells,PNU-74654 significantly decreases cell proliferation 96 h after treatment, increases early and late apoptosis, decreases nuclear beta-catenin accumulation, impairs CTNNB1/beta-catenin expression and increases beta-catenin target genes 48 h after treatment. No effects are observed on HeLa cells. In NCI-H295 cells, PNU-74654 decreases cortisol, testosterone and androstenedione secretion 24 and 48 h after treatment. The SF1 and CYP21A2 mRNA expression as well as the protein levels of STAR and aldosterone synthase are decreased in NCI-H295 cells after 48 h PNU-74654 treatment. In Y1 cells, PNU-74654 impairs corticosterone secretion 24 h after treatment but does not decrease cell viability^[1].