In addition, the results of Kaplan–Meier Plotter database showed that high expression of E2F1 predicted unfavorable OS of lung cancer patients, ovarian cancer patients, and breast cancer patients (HR = 1.95, 95% CI: 1.62–2.35, P = 1e-12; HR = 1.38, 95% CI:1.21–1.57, P = 1.1e-06; HR = 1.53, 95% CI: 1.26–1.85, P = 1.1e-05). Here, E2F1 is linked to lung cancer.