ERBB2 and breast carcinoma: Furthermore, we found that the anti-ErbB2 antibody trastuzumab used for ErbB2-positive breast cancer treatment upregulates Irf6 in BT-474 cells much more noticeably than in their variant selected for trastuzumab resistance by prolonged cell exposure to trastuzumab in 3D culture (Fig. 1f) [3].