BIRC5 and liver cancer: The expression of FEN1 in TCGA liver cancer tissues was positively correlated with that of MCM2 (r = 0.853, P = 0.000), BIRC5 (r = 0.809, P = 0.000), and RFC4 (r = 0.852, P = 0.000) (Figs. 6B–6D), suggesting that FEN1 may play as important a role in the progression of liver cancer as do MCM2, BIRC5, and RFC4.