Indeed, RUNX3 was shown to attenuate the stem cell–like traits of breast cancer cells: facilitating RUNX3 expression in both MCF‐7 and MDA‐MB‐231 cells led to reduced mammosphere formation capacity, indicated by reduced mammosphere forming frequencies and smaller sphere diameters; conversely, knock down of RUNX3 in MCF‐7 and MDA‐MB‐231 cells promoted the stem cell–like traits of breast cancer cells, indicated by more spheres formed and their larger size (Figure S2A‐C). The gene discussed is RUNX3; the disease is breast cancer.