Formerly known as GMP-140 and PADGEM, it is a selectin molecule that is synthesized by endothelial cells before (adjacent) tissues are infected. Thus “stored in advance,” the endothelial cells can present P-selectin molecules on the internal surface of the endothelium within minutes after an infection (of adjacent tissue) begins. This presentation of P-selectin molecules attracts leukocytes to the site of the infection, and draws them out of the bloodstream (the leukocytes “squeeze” between adjacent endothelial cells).