MAPK3 and obesity due to melanocortin 4 receptor deficiency: Because of its versatile role in biological processes, MAPK signaling pathway has been implicated in many human disorders ranging from cancer to obesity.22 Here, we found that MALAT1 knockdown could significantly change the levels of phosphorylated p38 MAPKs but has no effect on the levels of phosphorylated ERK1/2 or JNK1/2.