BCR and B-cell chronic lymphocytic leukemia: The observation that CLL arises from B cells with unmutated or mutated IG and that IG status of the CLL clone informs patient’s prognosis [14,15] has opened a long series of investigations on the meaning of B-cell receptor (BCR) structure and function in CLL, ultimately leading to the development of a class of drugs, commonly called BCR-associated kinase inhibitors, which are now dominating the therapeutic scene for patients with CLL.