INS and obesity due to melanocortin 4 receptor deficiency: In more detail, in the presence of high levels of miR-21, a relevant increase in the insulin-induced phosphorylation of AKT (Ser-473), the translocation of GLUT4 to the plasma membrane and the insulin-induced glucose uptake have been observed in concomitance with the decrease in the protein levels of PTEN, suggesting this miRNA as a new therapeutic target for metabolic diseases, such as T2D and obesity (99).