ABSTRACT
Cell migration is an essential component of normal development, inflammation, tissue repair, angiogenesis, and tumor invasion. After conception, selected cells of the developing mammalian zygote invade the uterine wall to establish the placenta, while the intricately programmed migration of other cells within the embryo shapes the complex form of the emerging organism [1,2]. The nervous system is another example of large-scale cell migration during fetal development. The growth of axons and dendrites is preceded by a phase of cell migration in which immature neurons (or neuroblasts) move from their birthplace to settle in some other location in order to make the right connections [3]. Certain kinds of white blood cells are able to migrate through the walls of blood vessels and into the surrounding tissues, actively seeking and engulfing sources of decay [4]. Migrating fibroblastic and epithelial cells heal wounds, and osteoclasts and osteoblasts are in constant movement as they remodel bone [5-7]. Tumor cell motility is also required for invasion and metastasis. The crawling malignant tumor cells that invade and disrupt tissue architecture account as much or more for the lethality of cancer as does uncontrolled growth [8].
