Lamellipodia are networks of microfilaments that span the front cortex in specific migrating cells and are organized as a meshwork of bundles with plus ends facing the cell membrane . The production of lamellipodia is a result of a growth factor binding to Cdc42 receptor on the cell membrane, which leads to the activation of a GTP-binding Rac protein that further transmits the signal to ARP2/3 (actin-related protein) , with the aid of a WAVE complex.
The function of lamellipodia is to contribute to cell movement. The locomotion is realized by the extension of the leading edge and the formation of a contact with the surface called adhesion. Due to contraction of the actin filaments, the cell body is able to follow the direction of the front lamellipodia. The membrane proteins used to form adhesions are called integrins, which after the disassembly of the back lamellipodium , are engulfed and brought to the front by endocytosis.