The week-long showcase features 330 of the top NFL prospects and gives those participants a chance to impress NFL executives, coaches and scouts through days of physical testing and interviews. The NFL Draft will be held in Philadelphia from April 27-29.
Nickerson, a fifth-year transfer from California, led the Illini with 107 tackles and added 5.5 tackles for loss and two interceptions.
Clements made 20 starts at Illinois and had 18.5 tackles for loss during the past two seasons.
Smoot, an All-Big Ten third team selection last season, totaled 30.0 tackles for loss and 13.0 sacks the last two seasons. Scout ranks Smoot as the No. 50 overall prospect in the 2017 NFL Draft.
Phillips broke out last season, becoming the first Illini to earn First Team All-Big Ten Team selection since 2011. He totaled 20.0 tackles for loss and 9.0 sacks.
Three Illini participated in the NFL Combine last year: DL Jihad Ward, RB Josh Ferguson and WR Geronimo Allison. Ward was selected in the second round by the Oakland Raiders, and Ferguson (Colts) and Allison (Packers) were signed as undrafted free agents and ended the season on their respective teams' rosters.
Illinois had no Combine participants in 2015 and just one participant, Jonathan Brown, in 2014.