CD77, also known as Gb3S, A14GALT, A4GALT1, is a type II membrane protein. It was found specifically expressed on Burkitt's lymphoma cells and on a subset of germinal center B lymphocytes. CD77 has been described as a receptor for Shiga Toxin and Verotoxin 1 (VT1), which is produced by Shigella dysenteriae and some strains of E. coli. It is used as a marker for germinal center stage B-cells. CD19 has been reported as a ligand for D77 and their interaction functions in adhesion and signal transduction at a specific stage of B cell development. Studies have shown that cross-linking CD77 induces apoptosis in some B cell lines.