Dexamethasone does not affect pathogenic Aβ accumulation and assembly on the HCSM cell surface. Near confluent cultures of HCSM cells were incubated for six days in the presence or absence of 25 μM Dutch mutant Aβ40 with or without daily administration of dexamethasone (1 μM final concentration). The HCSM cells were extensively washed, then fixed, and cell-surface Aβ was quantitatively measured by immunofluorescence labeling using mAb6E10 (A) or fluorescent thioflavin T binding (B). The data presented are the mean ± S.D. of triplicate wells read in five different fields per well from two to three separate experiments. (C) Alternatively, after incubation the HCSM cells were extensively washed, solubilized, subjected to SDS-PAGE, and subsequently analyzed by immunoblotting using mAb6E10.