In many cancer types including breast (Luporsi et al., 2012), lung (Jakobsen and Sorensen, 2013), brain (Abry et al., 2010), and prostate cancer (Fisher et al., 2013), the Ki-67 expression level represents a proliferation index, and Ki-67 overexpression predicts poor prognosis. This evidence concerns the gene MKI67 and cancer.