SCN9A and breast cancer: GJB2 and SCN9A have been linked to invasion and proliferation in prostate (Chen et al, 2019), lung (Campbell et al, 2013), gastric (Xia et al, 2016), and breast cancer (Liu et al, 2019), as well as metastasis (Ezumi et al, 2008; Naoi et al, 2007) and worse prognosis in several cancer types (Inose et al, 2009; Liu et al, 2019; Meng et al, 2022; Zhu et al, 2017).