The PCNA expression (28.6 ± 2.4%) in the US + PEG-ZnPP group was significantly lower than that in the US + PpIX and US + ZnPP groups (56.1 ± 2.3% and 47.4 ± 2.1%), indicating that the US + PEG-ZnPP group had significant inhibitory effects on the proliferation of ovarian cancer (Figure 7D,E). This evidence concerns the gene PCNA and ovarian cancer.