Fig. 4. Effect of cholesterol on Stx1B interaction with the apical surface of Caco-2 cells. (A) Stx1B and CTB co-localization in cells with disrupted LR. Confocal optical section through the apical surface of Caco-2 monolayers exposed to MßCD. Cells were double-labeled with Stx1B-Oregon Green 488 (green) and CTB-TMR (red). The overlay panel shows co-localization of both receptors (yellow). Bar, 5 µm. (B) Effect of cholesterol depletion on Stx1B binding plus internalization by Caco-2 cells. (C) effect of cholesterol depletion on Stx1B binding only by Caco-2 cells. (1) Control monolayers (n=7) with intact LR; (2) cells treated with filipin (n=7); (3) cells treated with MßCD (n=7); (4) cells incubated with cholesterol oxidase (n=7).