Post-transcriptional regulation plays a pivotal role in gene expression. In this study, the intracellular distribution of the murine cytoplasmic poly(C)-binding protein (alpha(CP2) gene transcript was investigated. The nucleocytoplasmic mRNA distribution of alphaCP2 was shown to change throughout the course of mouse development. Furthermore, in situ hybridization of the embryo revealed that the alphaCP2 transcript was widely distributed in the cytoplasm of endothelial cells and cardiac myocytes, but accumulated in the nuclei of other cells. In the adult, alphaCP2 was ubiquitously expressed and alphaCP2 mRNA was found to accumulate in the nucleus. In vitro experiments showed that the nucleocytoplasmic mRNA distribution of alphaCP2 mRNA was distinct from that of the GAPDH gene used as an internal control. These results suggest that the intracellular distribution of aCP2 mRNA is developmentally regulated in a gene and/or cell specific manner. (C) 2003 Elsevier Inc. All rights reserved.