E2F4 and Familial prostate cancer: CROSBY E2F4 TARGETS [28] included six putative E2F4 target genes downregulated in the LNCaP C4-2 cells (prostate cancer) at both 6 and 24 h following irradiation; these six genes were therefore presumed to help cells bypass irritation-induced G2 arrest and allow DNA damage to accumulate.