Gene targeting of Rac1 or Rac1/Rac2 in the T-cell lineage and the effect on peripheral blood cells. (A) Generation of T cell–specific Rac1- or Rac1/Rac2-deficient mice. To produce Rac1- or Rac1/Rac2-deficient T lymphocytes, Rac1^loxp/loxp or Rac1^loxp/loxp/Rac2^−/− mice were crossbred with Lck-Cre transgenic mice. (B) Expression of Rac1 in Lck-Cre–targeted thymocytes. WT, Rac1^−/−, or Rac1^−/−Rac2^−/− thymocytes were probed for Rac1 protein expression by anti-Rac1 Western blotting. Levels of β-actin in each sample were probed as loading controls. (C) Deletion of Rac1/Rac2, but not Rac1 alone, led to increased WBC and NE counts but normal LY counts in peripheral blood. (D) Deletion of Rac1/Rac2 but not Rac1 by Lck-Cre targeting caused decreased LY percentage and increased NE percentage in peripheral blood cells. (E,F) The effects of Rac1 or Rac1/Rac2 deletion on T- and B-cell productions in peripheral blood. PB cells were stained for TCRβ or B220 and analyzed by flow cytometry. The T- and B-cell numbers and percentages in PB were presented in panels E and F, respectively. n = 7 for each genotype. *P < .05; **P < .01. Error bars represent SD.