ERBB2 and neoplasm: The conjugates were also radiolabeled with 99mTc (T1/2 = 6 h, Eγ = 140 keV), through the N-terminally localized HEHEHE-tag (Scheme 1 in Supplementary Figure S1), and the influence of the glutamate spacer on hepatic uptake and overall biodistribution in a HER2-overexpressing preclinical murine tumor model was investigated.