Although the anti-ErbB2 scFv ML3.9 (KD=1 × 10−9) was sufficient to promote binding of ALM to MVM2 cells (ErbB2‘+’/ErbB3‘−’) at ALM concentrations above 10 nM, it should be noted that MVM2 cells express levels of ErbB2 equal to, or greater than, a number of ErbB2-positive breast cancer cells lines such as MDA-361/DYT2, T-47D and MDA-MB-231 when measured in vitro by quantitative flow cytometry (Table 1). This evidence concerns the gene ERBB3 and breast cancer.