To study loss-of-function of MCT-1, short hairpin RNA (shRNA) was used to silence the MCT-1 gene (shMCT-1) in 4T1 cells and greatly reduced the high cancer stemness features of mammosphere formation (Figure 1A) and expression levels of stem cell markers (BIM-1, Nanog, Sox-2, EpCAM) (Figure 1B), EMT inducers (ZEB1, Twist, vimentin) and oncogenic factors (IL-6/IL-6R, p-Stat3 (Ser727), p-Src (Tyr416)) (Figure 1C) compared with the unsilenced cells (scramble). The gene discussed is STAT3; the disease is cancer.