To further understand the stable phenotypes of the hypoxic TME-selected tumor cells, we established short-term in vitro cultures of the 1st xenograft-derived EGFP+ and EGFP− cells and interrogated the PI3K-AKT pathway that is strongly implicated in stem cell regulation and malignant progression including that of breast cancers [48–52]. This evidence concerns the gene AKT1 and breast cancer.