This crosstalk between RTK and GPCR signalling systems regulates several cellular processes; the dysfunctional signal integration between the two receptors may sometimes result in a variety of disease states, such as cardiovascular and renal disorders, obesity, metabolic syndrome, type diabetes mellitus, cancer, etc. The understanding of GPCR activation is fundamental for targeted cancer therapy. This evidence concerns the gene LPAR3 and obesity due to melanocortin 4 receptor deficiency.