Targeting knockdown of E2F1 resulted in the induction of ICAM-1 production and ICAM-mediated anti-tumor immunity to prostate cancer cells, highlighting a new functional signal circuit of E2F1 on immunoregulation of ICAM-1 beyond cell cycle and the potential of E2F1 knockdown act as an effective therapeutic approach against prostate cancer. The gene discussed is ICAM1; the disease is neoplasm.