Autologous T-cell activation leads to the upregulation of Rac signaling molecules in activated CLL cells. (A) Relative mRNA quantification in activated and nonactivated CLL cells using Taqman primers and probes (n = 6). (B) Relative Rac1 and Tiam1 expression after culturing CLL cells in direct cell cell-contact with autologous, anti-CD3/CD28-activated T cells or separated from the activated T cells by a 0.4-µm pore membrane filter (n = 6). (C) Relative Tiam1 mRNA expression in CLL cells that were cultured in the presence of either NIH/3T3-mock transfected fibroblasts or CD40L-transfected cells (3T3-CD40L) (n = 7). (D) Basal Rac1 activation in activated and nonactivated CLL cells, measured as described in Materials and methods (n = 3). Data represent means ± SD.