Apigenin possesses anti-obesity activity mainly by attenuating adipocyte differentiation by suppressing the mitotic clonal expansion and the adipogenesis-related factors, up-regulating the expression of multiple C/EBPβ inhibitors, and activating the COX2/PGE2 pathway for stimulation of UCP-1 via EP4 activation. The gene discussed is UCP1; the disease is obesity due to melanocortin 4 receptor deficiency.