EBP1, also known as PA2G4, is an RNA-binding protein which belongs to the peptidase M24 family. It can be detected n several cell lines tested, including primary and transformed cell lines. EBP1 also present in pre-ribosomal ribonucleoprotein complexes and may be involved in ribosome assembly and the regulation of intermediate and late steps of rRNA processing. This protein is a transcriptional co-repressor of androgen receptor-regulated genes and other cell cycle regulatory genes through its interactions with histone deacetylases. PA2G4 can interact with the cytoplasmic domain of the ErbB3 receptor and may contribute to transducing growth regulatory signals. EBP1 has been implicated in growth inhibition and the induction of differentiation of human cancer cells. It seems to be involved in growth regulation. EBP1 also mediates cap-independent translation of specific viral IRESs (internal ribosomal entry site).