The function of TFDP3 (transcription factor Dp family member 3, Ensembl gene identifier ENSG00000183434) is as follows. Competitive inhibitor of E2F-mediated transactivation activity. Impairs E2F-mediated cell-cycle progression from G(1) to S phase. {ECO:0000269|PubMed:16418725, ECO:0000269|PubMed:17062573, ECO:0000269|PubMed:20559320}.