PTPN22 inhibits activation of proapoptotic and enhances activation of antiapoptotic pathways in anti-IgM–stimulated CLL and B104 cells. (A) CLL cells were transfected with control (siCTRL) or PTPN22 (siPTP) siRNA as described in the legend to Figure 2. After 48 hours, cells were stimulated with soluble (left panel) or immobilized (right panel) anti-IgM for the indicated times. Cellular extracts were prepared and analyzed by immunoblotting with the indicated antibodies. Three independent experiments with similar results were performed. (B) B104 cells were transfected with control (CTRL) or PTPN22 (PTP) mRNA and stimulated with soluble anti-IgM as indicated. Cellular extracts were prepared and analyzed by immunoblotting with the indicated antibodies. One representative experiment of 3 is shown.