- Page 4 of 5 [DRAFT] - classification is based on nuclear mitotic number and the Ki-67 index,which are as follows:G1:Nuclear mitotic number <2/10HPF,Ki-67 proliferative index ≤2%.G2: Nuclear mitotic number 2～20/10HPF,Ki-67 proliferative index 3%～20%.G3 Nuclear mitotic number ＞ 20/10HPF,Ki-67 proliferative index ＞20%;