In this work, we describe for the first time the transcriptional profiles of BCR signaling components in CD5‐high and CD5‐low normal B‐cells, compare normal B‐cells to malignant B‐CLL lymphocytes, and confirm the role of ZAP70 as a unique kinase gene that allows for the distinction among different normal and tumor B‐cell subpopulations. The gene discussed is ZAP70; the disease is B-cell chronic lymphocytic leukemia.