ERBB2 and cancer: Our observation that HER2-HER3 phosphorylation in HER2-amplified cancers is restricted to the membrane compartment is entirely consistent with observations from FFPE studies of HER2-amplified cancers (Bai et al., 2013; Frogne et al., 2009; Kanomata et al., 2019; Kurebayashi et al., 2015; Trono et al., 2016).