Recent work showed that glycoprotein hormone erythropoietin (Epo) promotes breast tumorigenesis by activating JAK/STAT signaling in breast tumor-initiating cells (TIC) and promoted TIC self-renewal [20], although Epo is well known to regulate the production of red blood cells primarily by preventing apoptosis of erythroid progenitors [21]. This evidence concerns the gene EPO and breast neoplasm.