B-Cell Linker Protein (BLNK) is a cell membrane protein which contains 1 SH2 domain. BLNK is expressed in B cells and fibroblast cell lines, playing a important role in B cell receptor signaling. BLNK as a central linker protein, downstream of the B-cell receptor (BCR), bridges the SYK kinase to a multitude of signaling pathways and regulating biological outcomes of B-cell function and development. BLNK associates with the activation of ERK/EPHB2, MAP kinase p38 and JNK, modulates AP1, NF-kappa-B and NFAT activation. BLNK involves in BCR-mediated PLCG1 and PLCG2 activation and Ca2+ mobilization and is required for trafficking of the BCR to late endosomes. BLNK deficiency results in agammaglobulinemia type 4 and much more profound block in B-cell development.Alternative Names: B-Cell Linker Protein, B-Cell Adapter Containing a SH2 Domain Protein, B-Cell Adapter Containing a Src Homology 2 Domain Protein, Cytoplasmic Adapter Protein, Src Homology 2 Domain-Containing Leukocyte Protein of 65 kDa, SLP-65, BLNK, BASH, SLP65