Internalization and trafficking of SGN-CD33A. HNT-34 cells were labeled with SGN-CD33A and incubated for up to 24 hours at 37°C. At the indicated times, cells were fixed, permeabilized, and SGN-CD33A visualized using a fluorescently labeled secondary antibody (green). To study cellular localization of SGN-CD33A, cells were also stained with anti-Lamp1 antibody (red) and DAPI (blue) to mark lysosomes and nuclei, respectively. Arrows indicate examples of colocalized signal (yellow) observed in the merged images. Magnification, 630×, oil immersion.