BCR pathway activation and proliferation induced by BCR-specific antigens. (A) Activation of the BCR signaling pathway. The western blot analysis of the BCR signaling pathway shows a strong activation by the addition of SAMD14 in transfected TMD8 and U2932 cells expressing a SAMD14/neurabin-I-reactive BCR or by the addition of anti-IgM. The addition of the cognate antigens or anti-IgM antibody results in the upregulation of pTyr525/526 SYK, pTyr96 BLNK, pTyr759 PLCγ2, and pTyr223 BTK and led to an overexpression of c-Myc. (B) Proliferation induction of aggressive lymphoma cell lines by BCR-specific antigens. The columns (formazan at an OD of 450 nm) represent the proliferation of cells measured by reduction of tetrazolium salt to colored formazan by viable cells (EZ4U assay). Addition of epitope containing region of neurabin-I resulted in a significant increase in proliferation of TMD8 and U2932 cells expressing SAMD14/neurabin-I-reactive BCRs. Experiments were performed in triplicates for each condition and repeated for 3 times (***P ≤ .001).