High concentrations of free fatty acids in the blood are known to cause insulin resistance in muscle, but only after 5 hours. This suggests that a metabolite of the fatty acids may be responsible for this phenomenon. It is also known that an isoform of protein kinase C is activated during the process and that high concentrations of free fatty acids result in intramuscular accumulation of triacylglycerols. With this information, review the mechanism of activation of PKC and the pathway of triacylglycerol biosynthesis and suggest a metabolite that may be responsible for PKC activation.