ERBB2 and breast cancer: In this study, we identified nine ubiquitination sites within HER2 in SKOV3 ovarian cancer cells (Lys 716, Lys 724, Lys 736, Lys 747, Lys 765, Lys 854, Lys 860, Lys 883 and Lys 937), including a novel ubiquitin modification at lysine 883 previously not reported in breast cancer.