The results of the ggplot2 package (v3.3.3) algorithm analysis further confirmed that E2F1, E2F2, E2F3 and E2F5 expression were higher in primary PCa cancer tissues than in precancer tissues; however, E2F4 and E2F6 were lower in primary PCa tissues than in precancerous tissues (Figure 6B). Here, E2F4 is linked to cancer.