ABCG2 and glioma: Second, consistent with previous studies in human glioma, primary esophageal carcinoma and epithelial carcinoma cells [22], [39], [40], our data demonstrated increased drug sensitivity, down-regulation of p-PI3K and p-Akt, suppression of the ABCG2 and a decrease in the SP fraction in K562/ABCG2 and K562/IMR cells after LY294002 or rapamycin treatment.