Fig. 1.

BCR signaling. The binding of antigens to the B cell receptor leads to the phosphorylation of the intracellular immunoreceptor tyrosine-based activation motifs (ITAMs) of CD79A and CD79B. The phosphorylation of CD79A/CD79B initiates SYK activation, which then results in BTK activation and subsequent PLCG2 activation. This signal cascade ultimately leads to the activation of NF-κB and MAPK/ERK pathways, contributing to the survival and proliferation of CLL cells. BTK and PLCG2 mutations are detected in BTK inhibitor-resistant CLL cases