Recent discoveries revealed HMG-CoA is a reactive metabolite that can non-enzymatically modify proteins and impact their activity. Therefore, we predicted that inhibition of HMGCR by statins might increase HMG-CoA levels and protein modifications. Upon statin treatment, we observed a strong increase in HMG-CoA levels, and only a single protein was modified. Mass spectrometry revealed fatty acid synthase (FAS) was modified on active site residues and, importantly, the modification is located on non-lysine side-chains.