Yang X, Yang J, Chu Y, Wang J, Guan M, Zhu X, Xue Y, Zou H. Correction: T Follicular Helper Cells Mediate Expansion of Regulatory B Cells via IL-21 in Lupus-Prone MRL/lpr Mice. PLoS ONE. 2013 May 14;8(5). doi: 10.1371/annotation/4cdc693a-d3bb-4ca9-b094-29b061971a64.