A role for Lck in BCR ITAM phosphorylation has been suggested by studies in CLL cells treated with Lck inhibitors (24) and experiments demonstrating colocalization of the kinase with the CD79 chains, under the imposition of BCR ligation (25) or in the context of unstimulated subpopulations expressing exceedingly high levels of ectopic Lck (4), all of which may represent coincidental events. Here, BCR is linked to B-cell chronic lymphocytic leukemia.