Updated project metadata. 15-deoxy-delta12,14-prostaglandin J2 (15d-PGJ2) is an endogenous anti-inflammatory lipid derived from PGD2. One potential mechanism for its activity is the covalent modification of cellular proteins, via a reactive alpha,beta-unsaturated carbonyl group in its cyclopentenone ring, which in turn alters protein function. In order to identify the target proteins covalently modified by 15d-PGJ2 in human aortic endothelial cell (EC), EC were treated with biotinylated-15d-PGJ2, the modified proteins extracted by Neutravidin affinity-purification and the proteins were identified by LTQ Orbitrap mass spectrometer.