In spite of the observed peripheral lymphopenia, central (CD44highCD62Lhigh) and effector (CD44highCD62Llow) memory cells were equally represented among CD4+ (Fig. 6A) and CD8+ (data not shown) T cells derived from Rac1N/Rac3KO and Rac3KO littermates. The gene discussed is CD8A; the disease is lymphopenia.