2.1. Definition and characteristics of lamellipodia
Lamellipodia are characterized by a complex and dynamic actin cytoskeleton organization. The actin filaments within lamellipodia form a dense meshwork, creating a broad, sheet-like protrusion at the leading edge of migrating cells. This organization is largely regulated by the Arp2/3 complex and WASP, orchestrating the polymerization of actin filaments in a branched pattern [8]. The dynamic interplay between actin assembly and disassembly within lamellipodia allows for rapid membrane protrusion and retraction, facilitating efficient cell movement. Lamellipodia are essential for promoting cell motility by facilitating adhesion to the ECM and establishing focal contacts. The leading edge of lamellipodia contains membrane ruffles, allowing for dynamic interactions with the surrounding environment [19]. The continuous extension and retraction of lamellipodia create a wave-like pattern, propelling the cell forward. This dynamic behavior is crucial for processes such as chemotaxis, where cells navigate gradients of signaling molecules, and haptotaxis, where cells move along concentration gradients of matrix-bound factors [10,21,22].