MKI67 and neoplasm: This increase in proliferation index of xenograft tumours in mice treated with SP was further confirmed by immunohistochemistry with antisera for Ki-67 (indicated by the increased brown staining in SP treated tumours, arrowed in Figure 3D) and by quantitative stereology, which displayed 66±4 percent Ki-67 positive immunoreactivity in SP treated tumours in comparison to 35±9 percent in control tumours (Figure 3E; P<0.05).