We previously reported an efficient proteomic approach to identify matrix metalloproteinase (MNIP) Substrates from complex protein mixture. Using the proteomic approach, apolipoprotein C-II (apoC-II), which is a cofactor of lipoprotein lipase (LPL) and a component of very-low density lipoprotein and chylomicron, has been identified as a putative MMP-14 substrate. Cleavage of apoC-II, with various MMPs, demonstrated that apoC-II is cleaved most efficiently by MMP-14, and also by MMP-7, among the tested MMPs. The 79-amino acid residue apoC-II was cleaved between Asn(35) and Leu(36) by MMP-14, and between Phe(14) and Len(15) and between A Asn(35) and Leu(36) by MMP-7. Cleavage of apoC-II by MMP-14 markedly decreased LPL activity and would thus impair hydrolysis of triglycerides in plasma and transfer of fatty acids to tissues. Our result suggests that cleavage of apoC-II by MMPS Would be important for development of pathophysiological situations of apoC-II deficiency such as atherosclerosis. (c) 2005 Elsevier Inc. All rights reserved.