The uptake of both [125I]I-DARPin 9_29 and [99mTc]Tc(CO)3-DARPin 9_29 in HER2-expressing SKOV-3 xenografts was significantly higher than in HER2-negative Ramos lymphoma xenografts, which is a strong evidence of HER2-specific tumor accumulation. This evidence concerns the gene ERBB2 and lymphoma.