ERBB2 and breast cancer: Src activates AKT via inhibition of PTEN in breast cancer.24 Herceptin is a chemotherapeutic agent for HER2-positive metastatic breast cancer.49 The herceptin-resistant breast cancers are often identified with Src activation because the PTEN loss cannot dephosphorylate and inactivate Src.25 Src pathway is, therefore, recognized as an ideal therapeutic target for administration of breast cancer with PTEN mutation.