E2F-1: ProductsE2F-1 (adenovirus E2 gene promoter region binding factor 1; also retinoblastoma (RB)-binding protein 3/RBP3) is a 57 - 60 kDa nuclear member of the E2F/DP family of transcription factors. It has a dual function, mediating both cell proliferation and apoptosis in a context-dependent manner. Human E2F-1 is 437 amino acids (aa) in length. It contains a cyclin A: CDK2 binding site (aa 67 - 108), a DNA-binding region (aa 110 - 194), and an RB protein binding motif (aa 409 - 426) that, when engaged, inactivates E2F-1. There is one potential in-frame 23 aa substitution for aa 89 - 111. Over aa 264 - 437, human E2F-1 shows 89% and 80% aa identity to canine and mouse E2F-1, respectively.