To further validate the contribution of the RNase 1–EphA4 axis to breast tumorigenicity, we established mouse 4T1 mammary tumor cells, which harbored low endogenous mouse RNase 1 (mRNase 1), stably expressing mRNase 1 and vector control (Supplementary Fig. 13a, b). Here, RNASE1 is linked to breast cancer.