To investigate whether intracellular MAPK signaling in the hypothalamus of the offspring might be affected by maternal obesity, we determined total protein amount and phosphorylation of the MAP kinases extracellular signal regulated kinases 1/2 (ERK1/2), p38, c-Jun N-terminal kinase 1 (JNK1), and JNK2/3 in the hypothalamus of offspring of obese and lean mouse dams on P21. The gene discussed is MAPK3; the disease is obesity due to melanocortin 4 receptor deficiency.