Although AKT activation in breast cancer cell lines has also been reported under in vitro hypoxic conditions [63], we have found in this study that hypoxia in vitro alone is not sufficient to alter these signaling pathways, suggesting the new cellular phenotype exhibited by the ex vivo EGFP+ hypoxic cells most likely results from complex regulations in the hypoxic TME. This evidence concerns the gene AKT1 and breast cancer.