Finally, among protein markers tested, proliferation index Ki-67 showed an inverse correlation with TNFRSF11A_Δ7,8,9 expression (P = 0.017) indicating that as breast cancer evolves to a more aggressive disease state the expression of the TNFRSF11A_Δ7,8,9 diminishes (Figure 3C and Additional file 4). This evidence concerns the gene MKI67 and breast cancer.