Stromal Cell-Derived Factor 1 (SDF1) Is a Secreted Protein That

Multiple Choice

Stromal cell-derived factor 1 (SDF1) is a secreted protein that plays a major role in guiding the migration of various cells during development. It binds to a G-protein-coupled receptor on the surface of the migrating cell, which in turn activates a trimeric G protein containing a Gᵢ subunit. Pertussis toxin (PTX) modifies and inactivates the Gᵢ subunit. What would you expect to observe if migrating cells are treated with PTX?

A) They migrate toward the source of SDF1.
B) They migrate away from the source of SDF1.
C) They migrate in a certain direction chosen randomly.
D) They move in small steps in random directions.
E) They lose their motility.