– LSP1 (Lymphocyte Specific Protein 1) is a Protein Coding gene. This gene encodes an intracellular F-actin binding protein. The protein is expressed in lymphocytes, neutrophils, macrophages, and endothelium and may regulate neutrophil motility, adhesion to fibrinogen matrix proteins, and transendothelial migration. LSP1 is a lymphocyte-specific intracellular Ca2(+)-binding protein. LSP1 localizes to nascent phagocytic cups during Fcgamma receptor-mediated phagocytosis, where it displays the same spatial and temporal distribution as the actin cytoskeleton. Down-regulation of LSP1 severely reduces the phagocytic activity of macrophages, clearly demonstrating a crucial role for this protein in Fcgamma receptor-mediated phagocytosis. LSP1, expressed in endothelial cells, plays a pivotal role in regulating subsequent recruitment steps following leukocyte adhesion.