PABP4 (poly(A)-binding protein 4), also known as iPABP (inducible poly(A)-binding protein) was originally identified in a search for activation-induced genes in T-cells. It is one of five poly(A)-binding proteins encoded by independent genes whose products play roles in various aspects of mRNA processing. The PABP genes encode one nuclear and four cytoplasmic PABP proteins. PABP2/PABP (PABPN1) is the observed nuclear PABP. The cytoplasmic PABPs include PABP1 (PABPC1), PABP3 (PABPC3), PABP4/iPABP (PABPC4), and x-linked PABP5 (PABPC5). The cytoplasmic PABPs bear four RNA-recognition motifs (RRMs) that participate in binding poly (A). In T-cells, PABP4 is proposed to play a role in stabilizing labile mRNA.