Figure 3. Cell death in insulin receptor substrate (IRS)-1 knockdown. A: Cell Death ELISA of rat Müller cells transfected with IRS-1 shRNA alone and IRS-1 shRNA + beta-2-adrenergic receptor agonist, salmeterol for 6 h. Transfection with IRS-1 shRNA significantly increased cell death levels versus 5 mM glucose. Treatment with salmeterol (SALM) alone in Müller cells significantly decreased levels of cell versus 5 mM glucose and 25 mM glucose. Statistical significance was determined Mann–Whitney test (*p<0.05 versus 25 mM glucose, #p<0.05 versus 5 mM glucose, $p<0.05 versus SALM n=5 for ELISA assay).