PIK3CA and breast cancer: Serum/glucocorticoid-inducible protein kinase (SGK) is a key downstream signaling molecule of PI3K, which plays an important role in the regulation of cell proliferation, survival, invasion and metastasis.310 SGK-3, an isoform of the SGK family, plays an important role in cell proliferation and survival, especially in breast cancer, liver cancer, colorectal cancer, and prostate cancer.311,312 Recent studies have found that SGK-3 is overexpressed in breast cancer cells and that its inhibitor could significantly inhibit the proliferation of breast cancer cells.