4-Aminobenzoic-​2,​3,​5,​6-​d4 Acid Methyl Ester is an intermediate in the synthesis of DMABVIP(LA)d4 NHS Ester (D678402), which is a labelled DMABA NHS ester (D678400). DMABA NHS ester is a reagent that reacts with the primary amine group of PE lipids. DMABA NHS ester has been used in combination with DMABA NHS ester-d4, -d6, and -d10 to study relative changes in PE lipid abundance before and after radical oxidation.