ZAP-70 protein expression in CLL cell samples that expressed nonmutated (samples 1 through 5) or mutated (samples 13 through 17) immunoglobulin genes.

For immunoblot analyses, 10 μg protein lysate from each sample was loaded onto separate lanes of a polyacrylamide gel. Cell lysates were prepared from highly purified leukemia B cells (greater than 99% purity), Stable transfected Burkitt lymphoma B-cell line (BJAB), or mixtures of BJAB and isolated normal blood T cells containing 100%, 33%, 10%, 3%, or 1% T cells, as indicated at the top of the sample lanes. The immunoblots were probed with anti–ZAP-70 antibody to detect ZAP-70 protein, as indicated by the labeled arrow on the left-hand side of the Figure. The blots were stripped and reprobed with antibodies specific for β-actin, as indicated by the labeled arrow of the bottom row.