E2F1 and cancer: Aberrant expression of PTTG1 has been verified in pituitary, thyroid, uterine, ovarian, breast, gastric, and colon cancer.3, 4 Previous study also demonstrated that PTTG1 is overexpressed in HCC.29 PTTG1 overexpression can be induced by cancer‐associated fibroblasts,30 E2F1,31 Oct‐1,32 estrogen, and insulin.33 HBx can induce the abnormal accumulation of PTTG1 by inhibiting the ubiquitination of PTTG1 in HBV‐infected liver.34 However, the exact mechanism of PTTG1 overexpression in HCC was still unclear.