TOP2A and ovarian cancer: Moreover, the protein expression of hub genes including COL4A1 (Figure 7(a)), CDKN2A (Figure 7(b)), SDC1 (Figure 7(c)), and TOP2A (Figure 7(d)) was analyzed by using the Human Protein Atlas, and the protein expression levels of these genes were significantly higher in the ovarian cancer tissues than that in the normal ovarian tissues.