ESR1 and breast cancer: To assess whether INPP4B promotes the proliferation of PIK3CA-mutant ER+ breast cancer cells via Wnt/β-catenin signaling, assays were performed in the presence of the small molecule Porcupine (Porcn) inhibitors IWP-2 or LGK-974, which inhibit Wnt ligand secretion, or the Tankyrase (TNKS) inhibitor IWR-1-endo, which promotes constitutive β-catenin destruction complex stabilization43.