PDK1 and breast cancer: Firstly, elevated phosphorylation and activation of PDK-1 pSer241 were observed not only in BC cell lines (non-invasive MCF-7 and invasive MDA-MBB-468 cells) but also in invasive BCs (72/89, 80.9%), particularly in high-grade metastatic BCs (18/21, 86%) [55].