Liver regeneration is accompanied by a series of profound changes in hepatocyte gene expression. Similar changes in gene expression occur when hepatocytes are placed in primary culture. In the present study, we wished to determine the in vitro patterns of gene expression for several different functional classes of hepatocyte genes, and whether the changes in gene expression depended on the extracellular matrix. We therefore examined the expression of several genes which are known to change during hepatocyte proliferation in vivo or which are known to participate in different aspects of differentiated hepatocyte function. Hepatocytes were plated on collagen Type I, a matrix which supports cellular proliferation, or on the basement membrane matrix Matrigel, which supports a non-proliferating, differentiated hepatocyte phenotype. Total cellular RNA was collected after various times in culture, and cellular mRNA levels were determined by northern blot analysis for the following: transcription factors liver regeneration factor-1 (LRF-1) and CCAAT/enhancer binding protein delta (CEBPδ), the microsomal enzyme cytochrome CYP2A3 (rat orthologue of mouse CYP2A5) and the cell surface heparan sulfate proteoglycan, syndecan-2 (syn-2). Marked and rapid increases in LRF-1 and CEBPδ expression were observed on both matrix types. However, the expression of LRF-1 decreased rapidly on both matrices at 24 h, whereas CEBPδ expression was more delayed and returned to baseline values after 48 h. Messenger RNA for CYP2A3 decreased over 24 h on both matrices, but returned to 46% of control after 48 h on Matrigel which was significantly higher than hepatocytes plated on collagen. Finally, the expression of syndecan-2 was markedly decreased when hepatocytes were cultured on collagen Type I, but remained higher for hepatocytes grown on Matrigel at 48 h. For syndecan-2 it was shown that the half-life of syndecan mRNA was 1.5 fold longer on Matrigel than on collagen for the 3.4 kb mRNA, but no differences were found for the 2.2 and 1.1 kb messenger RNAs. These studies suggest that many changes in gene expression which occur in vivo during liver regeneration also occur in vitro during the transition to culture, and that some of these changes are influenced by the matrix upon which the cells are grown. Furthermore, these studies demonstrate that matrix-dependent changes in mRNA stability contribute, at least in part, to the observed changes in gene expression.