In many such cases, ‘tumor targeting’ may be more validly interpreted as ‘human-antigen targeting.’ Additionally, although the potential leakiness of tumor vasculature, known as enhanced permeability and retention (79,80), can contribute to tumor-preferential accumulation in vivo, we show here that HPK particles preferentially accumulated in the high HER3-expressing tumor rather than the low HER3-expressing tumor present on the same mouse. This evidence concerns the gene ERBB3 and neoplasm.