INS and obesity due to melanocortin 4 receptor deficiency: In a murine model of obesity and insulin resistance, dietary n-3 PUFAs were incorporated in the cell membrane phospholipids; they enhanced the membrane fluidity and the expression, affinity, and some insulin receptors (Das 1999) as well as glucose transporter-4 protein levels in adipose tissue (Peyron-Caso et al., 2002), thereby improving insulin sensitivity.