Insulin stimulation of fatty acid synthesis in human breast cancer cells.

Four human breast cancer cell lines were tested for their response to hormones with respect to the lactational function, fatty acid synthesis. Physiologic concentrations of insulin enhanced the incorporation of [14C]acetate into fatty acids in two of four cell lines tested. All cell lines had specific, high-affinity insulin receptors; therefore, the failure of two lines to respond could not be attributed to the absence of receptor. The effect of insulin involved an increase in the maximun velocity of incorporation rather than a decrease in the Michaelis constant.