Role of ceramide and oxidative stress in fructose-mediated insulin signaling. Tyrosine phosphorylation of IRS1 (A), phosphorylation of serine 307 on IRS1 (B), and tyrosine phosphorylation IRS2 (C) in primary hepatocytes in response to glucose (G) or glucose and fructose (GF) in the absence (- insulin) or presence (+ insulin) of insulin. When present fumonisin B1 (left) was at 50 uM and taurine (right) at 1% w/v. Data in graphs are the mean ± SDEV for 6 independent experiments performed in triplicate. Experiments were 4 h in duration. * significantly different from G (p < 0.05).