What is the test for a First Amendment retaliation claim?

To prevail on a First Amendment retaliation claim, plaintiff must prove "(1) he has an interest protected by the First Amendment; (2) defendants' actions were motivated or substantially caused by his exercise of that right; and (3) defendants' actions effectively chilled the exercise of his First Amendment right." Curley v. Village of Suffern, 268 F.3d 65, 73 (2d Cir. 2001). "Specific proof of improper motivation is required in order for plaintiff to survive summary judgment on a First Amendment retaliation claim." Id. (citation omitted).