Instagram CEO Adam Mosseri is expected to face sharp questioning when he testifies before a Senate subcommittee Wednesday afternoon, and he’s turned to veteran congressional investigations lawyers to prepare.

Mosseri has worked with attorneys at Kirkland & Ellis and Wilmer Cutler Pickering Hale and Dorr to ready himself for his first appearance before Congress. Kirkland partner Reginald Brown served as Mosseri’s lead outside counsel. Wilmer partner Joel Green also assisted in the preparations.