INSR and obesity due to melanocortin 4 receptor deficiency: However while insulin-stimulated glucose uptake correlated with insulin receptor activation, neither parameter was associated with the oxidative response to insulin: insulin increased both insulin receptor phosphorylation (Fig 1B) and glucose uptake (Fig 2A) in all cell lines to varying degrees, insulin promoted glucose oxidation only in obesity-associated tumors (Fig 2B and 2C).