However, JNK-1-deficient myeloid lineage cells show unaltered IL-6 expression and JNK-1 deficiency in these cells per se had no effect on the development of obesity-associated insulin resistance whereas other reports on bone marrow transplantation chimeras with JNK-1-deficient hematopoetic stem cells have yielded controversial findings [14]–[16]. This evidence concerns the gene MAPK8 and obesity due to melanocortin 4 receptor deficiency.