ATF4 and Insulin resistance: Interestingly, there was a marked decrease in the activation of the ER stress response and insulin resistance in the livers of the C57BL/6J-db/db mice treated with CTL due to decreases in the phosphorylation of eIF2α, IRE1α, and IRS-1 serine and decreases in the mRNA expression of ATF4, c-Jun N-terminal kinase, C/EBPα, and C/EBP homologous protein.