The function of BLNK was first illustrated in BLNK deficient DT40 cells, a chicken B-cell line, which exhibited an abrogated intracellular calcium mobilisation response and impaired activation of MAP kinases p38, JNK, and to a lesser degree ERK upon B-cell receptor (BCR) activation as compared to wild type DT40 cells. In knockout mice, BLNK deficiency results in a partial block in B-cell development, and in humans BLNK deficiency results in a much more profound block in B-cell development. Linker or adaptor proteins provide mechanisms by which receptors can amplify and regulate downstream effector proteins. The B-cell linker protein is essential for normal B-cell development.