Figure 3.

Analysis of Syk inhibitors on BCR pathway activation in CLL cells stimulated by CD40L. (A) CLL cells from three patients were incubated with CD40L⁺ or untransfected control L cells for 24h. CLL cells were treated with R406 (10 μM) or P505-15 (2 μM) or vehicle (DMSO). CLL cells were then processed and analyzed as in Figure 2. Syk (pY525/Y526) arcsinh median difference is shown. We found a significant difference between Syk activation in DMSO vs. R406 and DMSO vs. P505-15 (paired student’s t-test, P=0.03 and 0.001, respectively). Similar results were obtained with a separate experiment including 2 other patients. (B) Level of phosphorylation of downstream signaling proteins in the BCR pathway from experiment as in (A). Arcsinh median difference is shown for Akt (pS473), BLNK (pY84), Btk/Itk (pY551/Y511), ERK1/2 (pT202/Y204), and Syk (pY525/Y526). Heat map corresponds to −0.55 – +0.55 as indicated in the color bar.