Mpr1p, Pad1p N-terminal (MPN) domains without catalytic isopeptidase activity, found in eIF3fEukaryotic translation initiation factor 3 (eIF3) subunit F (eIF3F; EIF3S5; eIF3-p47; eukaryotic translation initiation factor 3, subunit 5 epsilon, 47kDa; Mov34/MPN/PAD-1 family protein) is an evolutionarily non-conserved subunit of the functional core that comprises eIF3a, eIF3b, eIF3c, eIF3e, eIF3f, and eIF3h, and contains the MPN domain. However, it lacks the canonical JAMM motif, and therefore does not show catalytic isopeptidase activity. It has been shown that eIF3f mRNA expression is significantly decreased in many human tumors including pancreatic cancer and melanoma. EIF3f is a potent inhibitor of HIV-1 replication; it mediates restriction of HIV-1 expression through several factors including the serine/arginine-rich (SR) protein 9G8, and cyclin-dependent kinase 11 (CDK11). EIF3f phosphorylation by CDK11 is important in regulating its function in translation and apoptosis. It enhances its association with the core eIF3 subunits during apoptosis, suggesting that eIF3f may inhibit translation by increasing the binding to the eIF3 complex during apoptosis. Thus, eIF3f may be an important negative regulator of cell growth and proliferation.