3T3-L1-mock and 3T3-L1-Grem2 cells were differentiated into adipocytes (adipocytes-mock and adipocytes-Grem2) for 9 days and then mixed with breast cancer MTV/TM-011 cells at the same ratio to form 3D spheroids in ultra-low attachment plates (Fig. 3a). The gene discussed is GREM2; the disease is breast cancer.