Moving to the University of Texas Health Science Center in Dallas, now the UT Southwestern Medical Center, Brown and colleague Joseph L. Goldstein researched cholesterol metabolism and discovered that human cells have low-density lipoprotein (LDL) receptors that extract cholesterol from the bloodstream. The lack of sufficient LDL receptors is implicated in familial hypercholesterolemia, which predisposes heavily for cholesterol-related diseases. In addition to explaining the underlying pathology of this disease, their work uncovered a fundamental aspect of cell biology - receptor-mediated endocytosis.