(AJ) Adipose tissue produces numerous adipokines, pro- and antiinflammatory cytokines and hormones which may influence the development of insulin resistance, type 2 diabetes mellitus and other comorbidities of the metabolic syndrome. The ability of adipose tissue to store lipids and thus protect other organs and tissues from ectopic lipid accumulation and development of insulin resistance (IR) is largely dependent on the adipogenic potential of preadipocytes. The amount and function of these cells may be the key factor in creating "healthy" adipose tissue or on the contrary "unhealthy" adipose tissue eventually leading to metabolic derangements. The regulation of the amount of body fat by converting preadipocytes into mature adipocytes may be crucial in the prevention and treatment of obesity and its comorbidities. One of the reasons for development of insulin resistance can be the inhibition of the differentiation process of preadipocytes into mature adipocytes with consequent ectopic lipid accumulation caused by the secretion of preadipocyte factor - 1 (Pref - 1). Pref - 1 has been discovered recently as a protein produced by preadipocytes but not by mature adipocytes. Pref - 1 is a member of the protein family sharing similarity with epidermal growth factors which regulate the differentiation of...