SLC9A1 and breast carcinoma: We additionally performed a proliferation assay to explore the relationship between viability and proliferation (for discussion see Supplementary Note 2), and found that SLC9A1 knockdown did not reduce the proliferation rate of FRCs, despite reducing their viability (Supplementary Fig. 6B)—a result that has been reported in the literature previously in breast cancer cells41, and which confirms that our model is generally reproducing a viability phenotype.