CD19, also known as B4, is a type I transmembrane glycoprotein that is a member of the immunoglobulin superfamily. CD19 is expressed on B cells, B cell progenitors, and follicular dendritic cells. It primarily acts as a B cell co-receptor in conjunction with CD21 and CD81. Upon activation, the cytoplasmic tail of CD19 becomes phosphorylated, which leads to binding by Src-family kinases and recruitment of PI 3-kinase.
Anti-Human CD19 (HIB19)-165Ho—100 Tests