Although recent approaches improved the diagnosis of breast cancer by giving interesting complementary information, like the evaluation of immunohistochemical biomarkers HER-2, progesterone receptors (PRs), estrogen receptors (ERs), and proliferation status (Ki-67) generally used to establish the prognosis and the predictive factors for the disease (Karlsson et al., 2014), the complex nature of these tumors mostly presents a significant challenge in therapeutic approaches. This evidence concerns the gene MKI67 and breast cancer.