Eukaryotic initiation factor 4E (eIF4E) is a key regulatory component that anchors the mRNA cap-binding complex (eIF4F) to the 5' end of capped mRNAs. eIF3, the poly (A)-binding protein, and the eIF4 proteins recruit mRNA to the 43S initiation complex to form the 48S initiation complex. The eIF4 proteins consist of the following: eIF4A, RNA helicase (46 kDa); eIF4B, RNA binding and RNA annealing protein (70 kDa); eIF4E (25 kDa), cap binding protein; eIF4H, which associates with eIF4B to stimulate eIF4A helicase activity (25 kDa); and eIF4G, which co-localizes all other proteins necessary for mRNA recruitment on the 40S subunit. As a principal initiation factor, eIF4E has the potential to influence expression of every protein in the cell. The mRNA subset that associated with eIF4E in p19 cells differed from the mRNA subset that associated with HuB or poly(A) binding protein, thereby suggesting that the former reflect distinct functional subsets of mRNAs whose expression is regulated differently at the translational level.