E2F4 is a transcriptional repressor that binds DNA cooperatively with DP proteins at E2 recognition sites (5'-TTTC[CG]CGC-3') to regulate cell cycle progression from G1 to S phase 1. E2F4 binds with high affinity to retinoblastoma family members (RBL1, RBL2, and RB1), functioning as a critical component of repressor complexes that maintain G0/G1 cell cycle arrest 2. Beyond canonical cell cycle control, E2F4 serves as a transcriptional activator in specialized contexts: it is specifically required for multiciliate cell differentiation, where it cooperates with MCIDAS and E2F5 to activate centriole biogenesis genes 1. In cancer pathology, E2F4 exhibits multifaceted roles. E2F4 is transcriptionally activated during cellular stress and differentiation 3, and aberrant E2F4 upregulation promotes gastric cancer progression by transcriptionally activating autophagy genes (ATG2A, ULK2), facilitating zinc homeostasis disruption and enhanced metastasis 4. Additionally, E2F4 can be co-opted by oncogenic factors; the ΔNp73α isoform hijacks the E2F4/p130 complex to reprogram its target gene selectivity, inhibiting proliferation-inhibitory genes in HPV-transformed and cancer cells 5. E2F4 cooperates with NRF1 and MYC to regulate genes controlling hallmark cancer traits including proliferation, invasion, and apoptosis 6. Thus, E2F4 functions both as a tumor suppressor through cell cycle control and as a context-dependent oncogenic driver in established cancers.