CLDN2 and obesity due to melanocortin 4 receptor deficiency: To further determine, causal role of these signaling in obesity-induced claudin-2 expression, Caco-2 cells were subjected to leptin or DCA-treatments with or without pharmacological inhibitors for NF-kB (Bay-11-7082; 20 μm) and JUN MAP Kinase (SP600125; 20 μm) signaling pathways.