This phosphorylation allows the dissociation of transcription factors, such as E2 promoter-binding factor (E2F) and the proto-oncogene c-Abl overexpressed or mutated in a number of malignant tumors, which can transactivate S-phase genes encoding for proteins that amplify the G1-to-S phase switch and are required for DNA replication [29]. Here, ABL1 is linked to cancer.