RPS6 and breast cancer: Although EGFR was suggested to be one of upstream regulators of PDK-1/AKT and Stat3 pathways (Engelman et al, 2005; Ivanov and Hei, 2005; Phillips et al, 2005), the role of EGFR activation plays in relation to PDK-1/AKT/mTOR/p70S6K/S6 cascade in breast cancers has not been firmly established.