Such evidence is particularly seen in CLL cells isolated from lymph nodes, which typically display high levels of BCR and NF-κB target genes [47] and express constitutively activated BCR signaling molecules, including LYN [48], SYK [49], PI3K [50], BTK [29], PKCβ [51], ERK [52], NF-κB [53], and NFAT [52]. Here, BTK is linked to B-cell chronic lymphocytic leukemia.