ERBB2 and breast cancer: This level of expression is equivalent to, or higher than, many ErbB2-positive breast cancer cells lines, such as MDA-361/DYT2 (3.7 × 105), T-47D (5.2 × 104) and MDA-MB-231 (2.8 × 104) when measured in vitro by quantitative flow cytometry (Table 1 and Tang et al, 2007).