{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"ZAP-70 is an abbreviation for Zeta-chain-associated protein kinase 70 (70 kDa). The protein is a member of the protein-tyrosine kinase family. ZAP-70 is normally expressed in T-cells and natural killer cells and has a critical role in the initiation of T-cell signaling."}]},{"type":"paragraph","children":[{"type":"text","value":"ZAP-70 in B-cells is used as a prognostic marker in identifying different forms of Chronic Lymphocytic Leukemia (CLL). ZAP-70 protein is expressed in leukemic cells in approximately 25% of Chronic Lymphocytic Leukemia (CLL) cases as well. ZAP-70 expression is an excellent surrogate marker for the distinction between the Ig-mutated (ZAP-70 negative) and Ig-unmutated (ZAP-70 positive) CLL subtypes and can identify patient groups with divergent clinical courses. The ZAP-70 positive Ig-unmutated CLL cases have a poorer prognosis."}]}]}