DKK1 and breast cancer: Increased mRNA expression of AXIN2 (1.9-fold), LEF1 (2.3-fold), and DKK1 (3.2-fold) was also observed in T47D cells expressing GFP-INPP4B (Supplementary Fig. 7a), demonstrating that INPP4B enhances Wnt/β-catenin signaling in PIK3CA-mutant ER+ breast cancer cells.