Fig. 6

Binding and uptake of trastuzumab (a) and trastuzumab-PE24 (b) by Her2-positive cells. MDA-MB-231 (Her2-negative) or MDA-MB-453 (Her2-positive) cells were incubated with trastuzumab or trastuzumab-PE24 for 30 min at 4 °C. For inducing the cellular endocytosis pathways, the MDM−/MB-231 cells were further incubated at 37 °C for 4 h. The cells were stained with anti-human IgG antibody-Alexa 488 and Hoechst, and the images were obtained using confocal fluorescence microscopy