ERBB2 and neoplasm: Considering that our previous studies utilized the MMTV-erbB2 transgenic mouse model (Liu et al., 2011; Zhu et al., 2014; Guo et al., 2017; Parris et al., 2017), further characterization is needed to understand the interactions between metformin and intrinsic pathways in mammary tissues of non-tumor models with similar genetic backgrounds, as well as the modulated signaling within the molecular network.