BCR responsiveness and leukemia behavior in murine and human CLL. (A) Kaplan-Meier plots showing time to development of overt leukemia in Eμ-TCL1, Eμ-TCL1/IgPtC, Eμ-TCL1/IgSm, and Eμ-TCL1/IgHEL transgenic mice. (B) Treatment-free and overall survival in CLL patients stratified according to response to anti-IgM stimulation. Cases that showed a >20% increase in pSYK or pERK levels after 10-minute stimulation with anti-IgM were classified as responders. Data are presented separately for the pSYK and pERK analysis because 14% of the cases (8/59) that were analyzed for both readouts showed discordant results.