DPP4 and diabetes mellitus: To investigate the effects of diabetic and non-diabetic plasma on JNK activation and DPP4 expression in the adipose tissue of diabetes, plasma harvested from Leprdb/db and Lepr+/+ mice was injected into the adipose tissue of Leprdb/db mice, and JNK activation and DPP4 protein expression in SVFs of adipose tissue were determined.