SCN1B and neoplasm: Up-regulation of SCN1B expression in ER+ tumours correlated with several genomic neighbours on chromosome 19q (Supporting Information Fig. S1c).26 However, mRNA levels of the two SCN1B splice variants, β1 and β1B,34 which are both expressed across a panel of BCa cell lines (Supporting Information Figs. S1d and S1e), were unchanged in MCF-7 cells following treatment with estrogen or fulvestrant (Supporting Information Fig. S1f), suggesting that SCN1B is not estrogen-regulated.