To study how different cancer cell models respond to the combination of PI3K (GDC-0941, also known as pictilisib) and MEK inhibitors (trametinib), we first determined the synergism profiles of three cancer cell lines to cotreatment; namely, MCF7, NTERA2, and HL60, which are models derived from breast cancer, testicular carcinoma, and AML, respectively. This evidence concerns the gene PIK3CA and breast cancer.