In response to a chemotactic signal,a cell forms structures to aid in locomotion.In lamellipodia,active Rac will stimulate F-actin polymerization at the leading edge via _____,whereas actin that will form stress fibers will be recruited by formin downstream of activation of this small GTPase _____.
A)Arp 2/3;Rho
B)Arp 2/3;Cdc42
C)WASP;Rho
D)Rho kinase;Cdc42

Question

Quizplus · Accepted Answer

Lamellipodia is a structure formed by the cell to aid in locomotion in response to a chemotactic signal. In this process, active Rac stimulates F-actin polymerization at the leading edge via Arp 2/3, while actin that will form stress fibers is recruited by formin downstream of activation of Rho, another small GTPase. Therefore, option A, which mentions Arp 2/3 and Rho, is the best choice. Option B is incorrect because Cdc42 is not involved in the formation of stress fibers. Option C is incorrect because WASP is not downstream of any small GTPase; rather, it is activated by Cdc42 and acts upstream of Arp 2/3. Option D is also incorrect because Rho kinase is not a small GTPase but rather a downstream effector of Rho.

In Response to a Chemotactic Signal,a Cell Forms Structures to Aid