Activation of signal transduction components of the BCR and downstream pathways. Phosphorylation of SYK, PLCγ, ERK, AKT, and p65 was assessed by flow cytometry in CD5⁺/CD19⁺ MCL cells from the PB and LN. (A) Comparison of the BCR and NF-κB signature scores between PBT and LNT samples concomitantly isolated from 2 patients providing matched cell samples. (B) Flow plots of PB and LN samples from a representative patient are shown. (C) Summary of phosphoprotein analysis (tested in duplicate) for matched PB and LN samples from the 2 patients shown in (A). (D) Pearson correlation r was used to measure the relationship of the percent tumor cells with detectable p-SYK and the corresponding BCR signature score in MCL-PBT (n = 14).