TNF-α-induced phosphorylation of IRS-1 at Ser 307 leads to insulin resistance in liver cells, and a JNK inhibitor largely abolishes the phosphorylation of IRS-1 at Ser 307 and restores insulin resistance, indicating that JNK activity is involved in the mechanism of TNF-α-induced insulin resistance. This evidence concerns the gene MAPK8 and Insulin resistance.