Considering both CD44 and CD49f could contribute to carcinoma progression and cancer metastases [40,41] and the ALDEFLUOR-positive breast cancer cells have also been reported to have cell invasion potential in vitro, which is related to metastases in vivo[42,43], we also performed Basement Membrane Extract (BME) invasion assay, using 10% fetal bovine serum as attractant, to examine the ability of ALDEFLUOR-positive and ALDEFLUOR-negative cells from GI-101A to invade in matrix gels. This evidence concerns the gene CD44 and breast cancer.