Matching the half-lives of positron-emitting radionuclides, such as copper-64 (64Cu, t1/2 = 12.6 h)9 and zirconium-89 (89Zr, t1/2 = 78.4 h)10, with the biological half-lives (t1/2 ~100 h) of anti-HER2 monoclonal antibodies (mAbs), such as Trastuzumab, prior to their attachment, has led to the successful imaging of HER2 expression in breast cancer patients11. The gene discussed is ERBB2; the disease is breast cancer.