Members of the UNC Board of Governors expressed concern Thursday that years of budget cuts are threatening the mission of the state's public university system to provide students a high-quality but affordable education. During a budget briefing in Chapel Hill, board members wrestled over whether to lift a self-imposed 6.5 percent annual cap on tuition increases to try to keep pace with the more than $1.2 billion in cuts and reversions in state taxpayer support since 2008.