 breast cancer stem cells, BCSCs, can be divided into two main categories, mesenchymalike EMT and epithelialike, MET. These two types of BCSCs differ in their location within the tumor, with mesenchymalike BCSCs being located near the tumor's invasive front while epithelialike BCSCs are located further away from the front. Additionally, both types of BCSCs share similar gene expression profiles with basal and luminal stem cells found in the normal breast. This suggests that BCSCs may have the ability to transition between EMT and MET states, which could explain how they are able to spread throughout the body and form new tumors. This article was authored by Sulin Lu, Yang Tsong, Dong Wang, and others.