On the other hand, hyperinsulinemia may foster the potential of (mitogenic) mitogen-activated protein (MAP) kinase-related signaling (Figure 2), which can also occur via IGF1 receptors due to increased free insulin-like growth factor-1 (IGF1) levels in obesity [17,18]. The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.