The mean value of the PCNA labeling index was 26.19 ± 1.25, 45.88 ± 2.20, 59.38 ± 1.04, and 72.77 ± 4.35 in normal mucosa, well-differentiated OSCC, moderately differentiated OSCC, and poorly differentiated oral squamous cell carcinoma (OSCC) respectively (Table 1, Figure 13). The gene discussed is PCNA; the disease is oral cavity squamous cell carcinoma.