In addition to mutations like ΔHER2 (Siegel et al., 1999), which results in a higher level of homodimer formation and phosphorylation, altered s-nitrosation in HER2+ breast cancer through GSNOR inhibition has also been identified to induce trastuzumab resistance (Cañas et al., 2016). The gene discussed is ERBB2; the disease is breast carcinoma.