PI3Ka and AKT mutations are detected in 30–50% of breast cancers [11, 12] and are associated with worse clinical outcomes in HR+ tumors [13], resistance to chemotherapy [13, 16], expecially to the anti-microtubule agent paclitaxel [28] and to anti-HER2 drugs [14], indicating that PI3K/AKT signaling activation can be clinically relevant. Here, PIK3CA is linked to breast cancer.