In conclusion, our results support the use of the spheroid assay as suitable for the study of stem cell traits in breast cancer cell lines showing an epithelial phenotype and expressing proper cell surface molecules (such as E-cadherin), though this assay is non-informative on cell lines that lack the expression of E-cadherin, either due to physiological reasons (such as cells on a clear mesenchymal phenotype as MDA-MB-231 cells) or mutational driven (such as deletion of E-cadherin gene region in SKBR3 cells). The gene discussed is CDH1; the disease is breast carcinoma.