Cell surface nucleolin co-localizes with LVS elongation factor Tu. THP-1 cells were incubated for 30 min with opsonized LVS and their interaction was observed by confocal microscopy at 63× magnification. Human cell surface was labeled with rabbit anti-nucleolin Ab diluted 1/200. Bacteria were labeled with murine anti-EF-Tu Ab diluted 1/2,000. Merging was observed with 3 × Zoom either with fluorescence light (right panel) or as bright field (left panel). Red arrows indicate colocalization of LVS with nucleolin present on cell surface. White arrows indicate LVS bound on cell surface in absence of nucleolin. These two photos are representative of five different experiments.