These observations are similar to our recent findings in which therapeutic resistance to lapatinib in preclinical models was associated with a switch in the regulation of breast cancer cell survival from HER2-HER3-PI3K in the treatment naïve state, to a HER3-EGFR-PI3K signaling axis that is resistant to inhibition by lapatinib [30]. Here, ERBB3 is linked to breast cancer.