MIB1 and cancer: The protein Ki67 has been suggested as a diagnostic biomarker in several tumors, being overexpressed in malignant tumor tissues compared to normal ones [7,8], and it correlates to tissue differentiation in an inversely proportional fashion; many studies have shown a correlation between the Ki67/MIB-1 labeling index and human cancer grading [4,9,10,11,12,13,14].