Galectin-12, also designated galectin-related inhibitor of proliferation 1 in mouse, is a 314 amino acid protein encoded by the human gene LGALS12. Galectin-12 is a member of the galectin family consisting of b-galactoside-binding proteins with conserved carbohydrate recognition domains. Galectin-12 binds lactose and may participate in the apoptosis of adipocytes. This protein is preferentially expressed in peripheral blood leukocytes and adipocytes. Galectin-12 is induced by cell cycle block at the G1 phase and causes G1 arrest when overexpressed. The galectin-12 gene is expressed in mouse preadipo-cytes and is upregulated when preadipocytes undergo cell cycle arrest, concomitant with acquisition of the competence to undergo differentiation in response to adipogenic hormone stimulation. Galectin-12 is an adipocyte-expressed protein which is downregulated by various insulin resistance-inducing hormones. As a result, galectin-12 may play a role in the pathogenesis of insulin resistance.