ERBB2 and breast cancer: To test the effect of MBP-1 overexpression on the endogenous ERBB2 gene, we transfected SKBr3 breast cancer cells with either a plasmid vector encoding a Flag-tagged MBP-1 protein (Flag-MBP-1) or an empty vector as a negative control; we then measured ERBB2 and c-MYC mRNA and protein expression levels by quantitative real-time PCR and Western blot, respectively (Figure 1A, B).