In addition, the protein expression of PCNA in tumor was detected by immunohistochemistry (Figure 6(h)) and the results showed that the average optical density of PCNA in the si-circRNA group and si-circRNA+miRNA mimics group was significantly lower than that in control group, while that in the si-circRNA+miRNA mimics group was lower than that in the si-circRNA group (Figure 6(i)). Here, PCNA is linked to neoplasm.