XBP1 and obesity due to melanocortin 4 receptor deficiency: Analysis of non-secreted upstream regulators indicated that EECs, Paneth cells, ILC1s, ILC2s, and CD4+ IEL-T cells expressed the highest levels of the genes downstream of the inflammatory signaling regulators (such as Myc, Nfe2l2, Xbp1, Stat4, and Tcf7l2), indicating those intestinal cells may play an important role contributing to obesity-associated inflammation and metabolic dysfunction (Fig. 9 B).