PIK3CA and breast cancer: Some of the amplified genes in either PDCs are well-known tumor related genes, such as AKT2, FGFR3, FGF10, SDHA, and PI3KCA. Interestingly, all three GSC PDCs harbor PIK3CA amplification that has also been reported in breast cancer, lung adenocarcinoma, and so on [39, 42, 43, 55, 56].