The third group included MKI67 and PCNA, the expression of which increased from the control group to the low-grade CIN group (p<0.05, MW), was similar in the low-grade and high-grade CIN groups (p>0.05, MW), and then increased in the CC group (p<1×10−15, MW; Figure 4). Here, PCNA is linked to cervical squamous intraepithelial neoplasia.