Rac GTPases play critical roles in early T-cell development by Celine Dumont, Agnieszka Corsoni-Tadrzak, Sandra Ruf, Jasper de Boer, Adam Williams, Martin Turner, Dimitris Kioussis, and Victor L. J. Tybulewicz Blood Volume 113(17): April 23, 2009 ©2009 by American Society of Hematology

Impaired T-cell development in the absence of Rac1 and Rac2. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Impaired thymic development and accumulation of aberrant TCRβ− DN4 thymocytes in the absence of Rac1 and Rac2 is intrinsic to the T-cell lineage. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Rac1 and Rac2 are required for efficient positive, but not negative, selection in the thymus. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Impaired pre-TCR–driven proliferation and accumulation of aberrant icTCRβ− DN4 thymocytes in the absence of Rac1 and Rac2. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Absence of Rac1 and Rac2 does not impair localization of DN thymocytes. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Increased survival of Rac1TRac2−/− icTCRβ− DN4 thymocytes. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology

Increased Notch-regulated transcripts in the absence of Rac1 and Rac2 and Vav-family GEFs. (A) Graphs show mean (± SEM) mRNA expression of Notch1, Notch3, Hes1, Deltex1, and preTα in DN3 and DN4 thymocytes from WT and Rac1TRac2−/− mice. Celine Dumont et al. Blood 2009;113: ©2009 by American Society of Hematology