Long time exposure to MIN6 cells does not oxidize LDLs. MIN6 cells were exposed to the 100 μg/ml of LDLs for 48 hours in the growth medium, and then the growth medium containing LDLs was collected and concentrated (line 2). On the other hand, the LDLs were also prepared by direct dilution with DMEM from stock solution (line 1). The oxidized LDLs were prepared as described in Materials and Methods (line 3). All three types of LDLs (about 1mg/ml protein) were subjected to agarose gel electrophoresis followed by the gel staining with oil-red.