MAPK8 and Insulin resistance: DUSP9 over-expression in genetically obese ob/ob mice on the other hand, improved glucose tolerance [19], while DUSP9 over-expression in 3T3-L1 adipocytes suppressed ERK1/2 and JNK activation, with a concomitant reduction in IRS1 serine phosphorylation that prevented the induction of insulin resistance [19].