In order to determine whether pre-labeling of Salmonella with paramagnetic nanoparticles might affect association of host cell proteins with the SCV, we infected the THP-1 human macrophage-like cell line with labeled bacteria, and at different time points post-infection, cells were fixed and immuno-stained with anti-Rab5 and anti-LAMP-1 antibodies, both standard markers for the SCV membrane [21]. Here, RAB5A is linked to infection.