In order to better understand the biological significance of sphere formation and determine which features might predict for this ability, we tested the abilities of 24 breast cancer and 3 normal breast epithelial cell lines (HBL100, MCF10A, SVCT) to form spheres by seeding at low dilution into non-adherent conditions in serum-free media containing EGF and FGF. This evidence concerns the gene EGF and breast carcinoma.