Fig. 9. Incubation with MßCD or water-soluble cholesterol has opposite effects on EGFR dimerization. HEp-2 cells were preincubated either with (+) or without (-) 10 mM MßCD for 15 minutes, or with 0.4 mg/ml water-soluble cholesterol for 30 minutes at 37°C. The cells were subsequently incubated with or without 10 nM EGF for 15 minutes on ice. The EGFR was crosslinked by the crosslinker BS³, before cell lysis, SDS-PAGE and western blotting, using an antibody to EGFR, as described in Materials and Methods. Bands at 170 kDa represent EGFR monomers, whereas bands at 340 kDa represent EGFR dimers.