ERBB2 and neoplasm: The level of the tumor uptake, 3.4 ± 0.7 %ID/g and 2.9 ± 0.7 %ID/g for [125I]I-DARPin 9_29 and [99mTc]Tc(CO)3-DARPin 9_29, respectively, was similar to the uptake of [99mTc]Tc(CO)3-labeled DARPin G3-D (4.45 ± 1.18 %ID/g) with the similar affinity to HER2 D (1.48 ± 0.01 nM according to SPR measurements) [22].