Discrimination between endothelial mediated transcytosis versus tumour cell mediated uptake is supported by our observation that a tumoricidal NBP (HerGa) elicits apoptosis of human TNBC cells but not human endothelial cells despite both cell types exhibiting similar cell surface HER3 levels (Supplementary Fig. 33). The gene discussed is ERBB3; the disease is neoplasm.