Fig. 6
From: The hypoxic tumor microenvironment in vivo selects the cancer stem cell fate of breast cancer cells
The PI3K/AKT pathway is required for maintenance of the CD44+/CD24− cancer stem cell (CSC) phenotype. The enhanced green fluorescent protein (EGFP)+ and EGFP− cells sorted from the 1st MDA-MB-231 xenografts underwent serum starvation overnight. After serum stimulation, phosphorylation of AKT (a), PI3Kp85 (b), mTOR (b), and ERK1/2 (c) was analyzed using Western blots. d Serum-stimulated AKT phosphorylation in the parental MDA-MB-231/HRE-EGFP cells under normoxia and hypoxia (1% O2). e Increase in the CD24+ population induced by the PI3K inhibitor LY294002 (20 μM). f Quantitative RT-PCR analysis of expression of CD24 and CD44 genes in response to LY294002. These observations are confirmed by independent experiments