Cholesterol content in J774 and U937 cells.

Cholesterol was extracted from cells using 10 mM MβCD at 37°C for 30 min. U937 cells deficient in endogenous cholesterol synthesis were grown in RPMI medium supplemented with 10% normal fetal calf serum or with 10% lipoprotein-deficient serum from fetal calf (delipidated serum) for 48 h. Cholesterol content was determined using the Amplex Red Cholesterol Assay Kit (Molecular Probes). Values represent the mean ± S.D. obtained from three independent experiments. N.D., not detectable.