ERBB2 and breast cancer: Binding of bTrast, bPert and bCet to SKBR3 and BT474 ErbB2+ breast cancer cells, which express different levels of EGFR and ErbB2, was similar to the binding of the parental antibodies while, binding of the negative control anti-CD20 biotinylated Rituximab (bRit) was only visible on AvidinOX-conjugated cells, as expected (Supplementary Figure 1).