MiR-21 is overexpressed in many tumors and considered as key regulator of oncogenic processes. It is also highly expressed in CM and cardiac fibroblasts and apparently plays an important role in cardiac metabolism. Both miR-21 regulation as well as PLB-SERCA2a interaction are known to be regulated via b-adrenergic receptor signaling. In the dairy cow, late gestation and early lactation are periods marked by major changes in the sensitivity and responses of tissues to hormones involved in homeostasis, such as insulin. Indeed, during these periods, there is a moderate decrease in peripheral tissue insulin sensitivity,HDM201 promoting the mobilization of non esterified fatty acids and amino acids and facilitating the preferential use of nutrients by the fetus or mammary gland. The decrease in insulin sensitivity occurring in adipocytes during late gestation and early lactation in dairy cows remains poorly understood. Insulin acts by binding to the insulin receptor, a tyrosine kinase receptor, on cells. Following insulin binding, the IR phosphorylates various substrates, including IRS-1 and IRS-2, which interact with several intracellular proteins to activate different signaling pathways, including the PI3K/Akt and MAPK ERK1/2 pathways. Sadri et al. studied the expression of genes encoding components of the insulin receptor signaling pathway in adipose tissue during the dry period and in early lactation, in dairy cows. They observed a significant decrease in insulinresponsive glucose transporter gene expression in subcutaneous adipose tissue around the time of parturition. However, the levels of phosphorylation of IR signaling components have never been investigated. Adipokines factors secreted by the adipose tissue may be involved. In particular, resistin is known to decrease insulin sensitivity in rodents, whereas its effect in humans is unclear. Resistin is a protein consisting of 108 amino acids in humans, 114 amino acids in mice, and 109 amino acids in cattle; it belongs to the “resistin-like molecules” or “FIZZ” family. It consists of homodimers linked by disulfide bridges. Resistin is produced directly by the adipocytes in mice, whereas it is produced by macrophages and transported to adipocytes in humans. Plasma resistin levels are correlated with the degree of insulin resistance in mice,BMS-935177 whereas conflicting results have been reported concerning this aspect in humans. In bovine species, the localization in adipose tissue and the role of resistin in lipolysis are still unknown. In mice, plasma and adipose tissue levels of resistin decrease in response to thiazolidinediones and increase during obesity. Very little is currently known about the mode of action of resistin. No receptor has yet been clearly identified and the signaling pathways used remain unclear. Recent studies have suggested that resistin may bind a receptor tyrosine kinase called ROR1 in murine pre-3T3-L1 adipocytes, or to TLR4 in the hypothalamus of mice. The adipose tissue of dairy cows also produces several adipokines, including resistin. Komatsu et al. showed that levels of resistin gene expression in the adipose tissue were significantly higher in lactating than in non lactating cows, whereas the opposite pattern was observed in the mammary gland.