Rapid internalization and degradation of endostatin.

IBE cells or Swiss 3T3 cells were incubated in the absence (control) or presence of 10 μg/mL biotinylated endostatin for different periods from 5 minutes to 150 minutes. Binding was identified using Alexa 488-labeled avidin l that was added to the control and endostatin-incubated samples, which subsequently were analyzed microscopically (Bar, 10 μM). Upper panels show IBE cells cultures; lower panels show Swiss 3T3 cell cultures.