Oculopharyngeal muscular dystrophy is caused by expansion of a (GCG)n trinucleotide repeat in the poly(A) binding protein 2 (PABP2) gene. The pathological hallmark of oculopharyngeal muscular dystrophy is the accumulation of intranuclear inclusions in muscle fibers. To test whether the polyalanine expansion of PABP2 directly leads to the formation of the nuclear aggregates, both normal and expanded PABP2 cDNAs were expressed in COS-7 cells. We find that expression of mutated PABP2 protein is sufficient for its accumulation as intranuclear inclusions.