Furthermore, significantly mutation genes in breast cancers have been identified, and these genes significantly affect pathways of functional or cellular processes, including the TP53 or PI3K pathway (e.g., PIK3CA, PTEN, and AKT1), MAPK/JNK signaling (e.g., MAP3K1, MAP2K4, and NF1), transcription factors and regulators (e.g., GATA3, RUNX1, and CBFB), splicing factors (e.g., SF3B1), and chromatin remodelers (e.g., MLL3 and ARID1A). This evidence concerns the gene PIK3CA and breast cancer.