Being a sponsor simply means they are contributing funds to the IBD organization to run this event. It gives Celgene a large presence as the main sponsor with their name plastered all over the event. Event sponsoring is simply a marketing tool. The sponsor does not decide who gets invited to present, that decision is up to the Crohn's & Colitis Foundation. Notice the wording "hosted by" from press release.

"The day-long conference, hosted by the Crohn’s & Colitis Foundation and sponsored, in part, by Celgene Corporation,"