Question

The formation of a lamellipodium of constant size at the leading edge of a migrating cell requires:

	A.	Assembly of a branched nextwork of actin microfilaments (F-actin) nucleated at branch points by the Arp2/3 complex.
	B.	Dissasembly of actin microfillaments (F-actin) stimulated by cofilin at the rear of the advancing lamellipodium.
	C.	Disassembly of actin microfillaments throughout the cell.
	D.	A and B
	E.	A, B, and C

Answer 1

Lamellopodium is an actin mesh and during its formation there is an assmbly of actin microfilaments where Arp 2/3 complexes are present at the junctions of microfilaments which help in creating the mesh and branching points for the extension of new actin microfilaments. these lamellopodium help in mobility of cells. however the binding of cofilin at the rear end (pointeed end) causess disassembly of the filaments to prevent further polyemerization. in this way both the factors work together to maintain a constant size of the lamellipodium

hence option a is the appropraite option D is the correct one.