CXCL12 and obesity due to melanocortin 4 receptor deficiency: Studies on mice MSCs suggest that obesity skews differentiation of MSCs toward adipocytes at the expense of osteoblasts.54,64 As described previously, CXCL12 from osteoblasts are important for the maintenance of lymphoid progenitors, and adipocyte over osteoblast differentiation could potentially have a negative impact on production of lymphoid cells.