Illinois Teachers' Retirement System, Springfield, is searching for an active domestic large-cap growth equity manager to run $664 million. Trustees of the $30 billion plan today terminated the portfolio's previous manager, MFS, for performance and ongoing securities trading litigation, according to a statement. MFS had been on the plan's watchlist. The plan's consultant, Callan Associates' Chicago office, is handling the search. Assets will be placed temporarily in S&P 500 index funds run by State Street Global Advisors. David Oliveri, an MFS spokesman, declined comment.