Also, a significant correlation was found between 18F-FDG uptake and the number of Ki67 positive cells (R2 = 0.79, p < 0.05, data not shown), supporting 18F-FDG-PET as a good surrogate for tumor proliferation activity in ductal breast carcinoma [28], corresponding to the BC cells in our model. Here, MKI67 is linked to breast cancer.