The nuclear orphan receptor Nr4a2 induces Foxp3 and regulates differentiation of CD4+ T cells by Sekiya, T, Kashiwagi, I, Inoue, N, Morita, R, Hori, S, Waldmann, H, Rudensky, A, Ichinose, H, Metzger, D, Chambon, P, Yoshimura, A