The Bengals and the other 31 teams were in attendance at Oklahoma's pro day. The Bengals, along with the Bills and Bears, actually sent two representatives to catch all the action, according to the Sooners' official Twitter account.
There are several players the Bengals are likely interested in working out at the school's pro day. Offensive tackle Lane Johnson could be one, especially if the team loses Andre Smith. Another could be quarterback Landry Jones, though if they're looking for a backup they probably wouldn't select one as high as Jones is likely to go. There's also wide receiver Kenny Stills and safety Tony Jefferson could interest the Bengals as well.
The Bengals are in need of several of the positions that are represented at Oklahoma's pro day and there's a decent chance that they're watching someone that they'll eventually select in the draft.