In this week's PNAS Early Edition, researchers at the University of California, Los Angeles, and their collaborators, show that in the absence of GPIHBP1 — a protein found in capillary endothelial cells that "shuttles lipoprotein lipase [LPL] from subendothelial spaces to the capillary lumen" — LPL-mediated triglyceride hydrolysis is blocked, and plasma triglyceride levels are elevated.