Examples of cancer biomarkers routinely used in the clinic include α-fetoprotein (AFP) for diagnostics and management of testicular cancer [27], MUC16 (cancer antigen 125 or CA-125) for ovarian cancer [28], ERBB2 (HER2) protein for breast cancer [29], and prostate specific antigen for prostate cancer [30]. Here, ERBB2 is linked to cancer.