ERBB2 and breast cancer: Turpin and colleagues reported that d16HER2-expressing mammary tumor cell lines derived from ErbB2ΔEx16-transgenic mice or normal murine mammary gland (NmuMG) transfected with d16HER2 are resistant to the anti-HER2 therapeutic trastuzumab emtansine (T-DM1), an antibody–drug conjugate, whereas control cells that express wtHER2 are highly sensitive to it [39].