Loading HAS cells with cholesterol. HAS cell cholesterol was enriched by incubating cells with 1 ml cholesterol-MβCD complex (1:10, cholesterol: MβCD molar ratio) for 10 min at 30°C. Total cell lipids were extracted by 1:1 methanol:chloroform. Total cell free cholesterol (without cholesterol ester) of control cells and of cholesterol-MβCD–treated cells was determined by Amplex Red method and expressed in μg/mg of total left over cell protein after lipid extraction. Cholesterol oxidase treatment of cells, which lowered membrane-free cholesterol by oxidation, gave a reasonable estimate of free cholesterol available at the membrane. Membrane cholesterol oxidation was achieved by incubating cells with the enzyme cholesterol oxidase (COD) and 700 U of catalase, for 10 min at 30°C. Another way used to lower membrane cholesterol was to extract it from membranes using MβCD. For extraction of membrane cholesterol, cells were incubated with 10 mM MβCD in Sf9 culture medium (without FBS) for 10 min at 30°C. Thus HAS cells can be enriched with cholesterol and, alteration of the cholesterol level after enrichment with COD and MβCD treatments indicates, loaded cholesterol was in HAS membrane. (values: mean ± SEM, n ≥ 5).