Fig. 1. Consequence of silencing nuclear β-catenin for mouse preimplantation embryo development. (A,B) Immunofluorescence localization of total (A) and dephosphorylated (active, B) β-catenin in mouse preimplantation embryos. (C-F) Recombinant Dkk1 protein (5 µg/ml) and PKF115-584 (0.1 µM) block nuclear import of active dephosphorylated β-catenin and Cdx2 expression in preimplantation embryos, without interfering with the cellular level of total β-catenin and the development of 2-cell embryos to blastocysts in culture. Two-cell embryos recovered by flushing day-2 pregnant oviducts were cultured in groups of 5-10 in 25 µl of M16 medium under silicon oil in an atmosphere of 5% CO₂ and 95% air at 37°C for 72 hours and the number of blastocysts that developed was recorded. Experiments were repeated 3-5 times. The numbers above the bar in C indicate the number of blastocysts developed per the number of cultured 2-cell embryos. Cy3-labeled active β-catenin in red, SYTO-13-labeled nuclei in green, and the merge in yellow. ICM, inner cell mass; Tr, trophectoderm; veh: vehicle; PKF, PKF115-584. Scale bars: 50 µm.