MAPK8 and obesity due to melanocortin 4 receptor deficiency: Zhang et al. demonstrated that PTH-rP induces insulin expression by dephosphorylating c-Jun N-terminal kinases JNK1/2 in pancreatic beta-cells, while Roca-Rodríguez et al. found that PTH-rP mRNA expression in visceral adipose tissue seems to be related to obesity-associated insulin resistance [37,38].