FIG. 1.

Uptake of cholera toxin into MA104 cells treated with sterol-binding drugs. MA104 cells were mock treated (A and B) or pretreated with MβCD (10 mM) (C and D), filipin (15 μg/ml) (E and F), or nystatin (50 μg/ml) (G and H), as detailed in Materials and Methods, and then were incubated with Alexa 488-Ctx. The fluorescent signals are shown in panels B, D, F, and H; panels A, C, E, and G show the corresponding phase-contrast images.