 The study examined four different endocytotic uptake mechanisms in two types of cells, mouse macrophages and human alveolar epithelial type 2 cells. The researchers found that the uptake of 40 nanometers polystyrene nanoparticles was affected by the presence or absence of certain proteins and lipids. They concluded that multiple endocytic pathways are involved in the uptake of these particles, including phagocytosis, macropinocytosis, clathrin-mediated endocytosis, and cavelin-mediated endocytosis. This article was authored by Dagmar A. Kuhn, Demetri Van Heck, Benjamin Michen, and others.