In support of a direct response, conditioned media from the luminal EO771 BC cell line and the HER2/neu overexpressing NF639 line significantly repressed aerobic ATP production in differentiated C2C12 myotubes, whereas media conditioned by either the normal mammary epithelial cell line EpH4-EV or C2C12 myoblasts did not (Fig. 6e). This evidence concerns the gene ERBB2 and breast cancer.