CD4 and colitis: CD4+CD25− effector T cells from colitic Gαi2−/− mice (KO-Teff), or CD4+CD25− effector T cells from WT mice (WT-Teff) were transferred with or without CD4+CD25+ Treg from Gαi2−/− mice with colitis (KO-Treg) or WT mice (WT-Treg) at a 4∶1 Teff∶Treg ratio into RAG2−/− recipients.