CD44 and breast cancer: To further gain insights into the mechanism underlying hRNase 1–EphA4 induced stem-like cell properties, we first ectopically expressed EphA4 in ZR-75-1 luminal A breast cancer cells (Supplementary Fig. 11a) and observed the upregulated sphere formation (Fig. 6a and Supplementary Fig. 11b) and the enriched population of CD24−/CD44+ stem-like cells (Fig. 6b, c), whereas shRNA knockdown of hRNase 1 abrogated those effects.