TCF7L1 and breast cancer: We also examined the expression of these genes in a separate cohort of 698 luminal (ER/PR+) breast cancers using the TCGA dataset (Supplementary Fig. 8), where PIK3CA-mutant cancers displayed significantly higher expression of eight Wnt genes (LEF1, TCF7L1, TCF7L2, CTNNB1, LRP6, SFRP2, WNT5A, and MSX2).