ABSTRACT
Chemokines are a class of proteins that induce and direct cell migration. Chemotaxis refers to the migration of cells in a direction determined by a gradient of a diffusible chemical, such as a chemokine. Cells are attracted to and migrate toward the source of a chemokine; thus, chemokines function as chemoattractants. When present in a uniform concentration in the environment (i.e., no gradient), chemokines affect the speed, but not the direction, of cell migration. Stimulation of migration in random directions in this manner is called chemokinesis. Nondiffusible signals on the extracellular matrix or the surface of neighboring cells can also direct cell migration. The
effect of a chemokine or other signals on the migration of a speci¦c cell type can be studied using in vitro assays.
