LYN inhibition abrogates HS1-Y397 phosphorylation and reduces VAV1 and ERK activation. In the first 4 upper panels, the phosphorylation status of LYN-Y396, HS1-Y397, VAV1, and ERK was evaluated by WB (representative of 6 different patients) before and after treatment with 100 nM dasatinib for 1 hour, anti (α)-IgM for 5 minutes, CXCL12 for 5 minutes, or with a combination of dasatinib/α-IgM or dasatinib/CXCL12. Immunoblotting shows that blocking LYN kinase activation by dasatinib interferes selectively with HS1-Y397, VAV1, and ERK activation, also in the presence of BCR and CXCR4 stimulation by α-IgM and CXCL12, respectively, though at a more limited degree in the case of ERK. In the 4 lower panels, total levels of each protein tested are displayed as control. +, presence of the treatment; −, absence of the treatment.