ABCA1 efflux from cAMP J774 cells was the Probucol sensitive efflux measured after 4h incubation with 2.8% apoB-depleted serum from specimens with similar HDL-C (HDL-C±6%) at either the 25th percentile (open circles: HDL-C=48, range=45-51, n=22) or the 75th percentile (open triangles: HDL-C=73, range 69-77, n=18). The specific contribution of ABCA1 to cholesterol efflux from cAMP treated J774 macrophages was significantly associated to the serum level of preβ-1 HDL (r2=0.425, p=0.0002, n=29) measured by 2D gels. All procedures as in methods.