ERBB2 and neoplasm: The [18F]AlF-NOTA-HER2 affibody with a Kd value of 52.25 ± 3.68 nM showed good uptake in the HER2+ tumor cell, and the in vitro uptake was blocked by excess cold HER2 affibody, indicating that the probe had high target-binding affinity and specificity in HER2+ cells.