We determined the expression of an endogenous lectin, galectin 4, in the rat small intestine during postnatal development. The mRNA levels of galectin 4 did not change significantly between birth and adulthood. In contrast, the protein was present at higher levels after than before weaning, and the potential ligands for galectin 4 were more highly represented in the enterocyte microvilli of weaned than of suckling rats. These results suggest possible differences either in galectin 4 mRNA stability, in its translation regulation or in the protein stability