PGR and neoplasm: Barbie et al27 found that IKBKE was overexpressed in breast cancer cell lines, including TNBC (triple‐negative breast cancer) cell lines that were negative for ER (estrogen receptor), PR (progesterone receptor), and HER2 (human epidermal growth factor receptor 2), and that knocking down IKBKE in TNBC cell lines decreased tumor cell proliferation and colony formation.