Finally we confirmed the differential ability of insulin to stimulate glucose oxidation in obesity-associated versus obesity-independent tumor cells in studies of absolute glucose oxidation measured by trapping 14CO2 generated by oxidizing 14C6 glucose (Fig 2C): incubation with insulin doubles colon cancer cell glucose oxidation, while melanoma cells show no change in glucose oxidation rates when insulin is added to media. Here, INS is linked to melanoma.