Acetylated Low Density Lipoprotein, labeled with 1,1’-dioctadecyl – 3,3,3’,3’-tetramethyl-indocarbocyanine perchlorate(see DiI-Ox-LDL ). modified low-density lipoprotein (LDL) including Ox-LDL, Ac-LDL can bind to cell membrance via class A scavenger receptor (SR-A) , CD36 and LOX-1 etc. When cells are labeled with DiI-Ac-LDL, the lipoprotein is degraded by lysosomal enzymes and the DiI (fluorescent probe) accumulates in the intracellular membranes. It can be used to quantify uptake of modified LDL. It also be used to identify isolated cells including vascular endothelial cells, macrophages, and endothelial progenitor cells(EPC).