PIK3CA and breast cancer: The Tankyrase1/2 inhibitor XAV939, which stabilizes the β-catenin destruction complex and suppresses Wnt/β-catenin signaling, sensitized PIK3CAH1047R expressing mammary tumor cells derived from a doxycycline inducible-PIK3CAH1047R mouse to LY294002, a non-selective PI3Kα/δ/β inhibitor that also inhibits other PI3K-related kinases as well as unrelated proteins, although little effect was observed in mammary tumor cells derived from PIK3CAH1047R transgenic mice or PIK3CAH1047R ER− breast cancer cells for unknown reasons [99].