PIK3CA and breast cancer: In general, the luminal A breast cancer subtype displays mutations in phosphatidylinositol 3-kinase (PIK3CA) (~49%), mitogen-activated protein kinase (MAP3K1) (~14%), GATA binding factor 3 (14%), TP53 (~12%), and MAP2K4 (~12%) and loss of Phosphatase and tensin homolog deleted on chromosome ten (PTEN) (13%), among others.