Thus, the ZAP70‐high and ZAP70‐low subgroups of B‐CLL have different transcription profiles for all BCR signaling molecules, except for LYN tyrosine kinase gene, which tends to be downregulated in all B‐CLL lymphocytes compared to normal CD5‐high and CD5‐low B‐cells. Here, CD5 is linked to B-cell chronic lymphocytic leukemia.