BCR and B-cell chronic lymphocytic leukemia: The relevance of BCR signaling in CLL is underlined by the clinical success of BCR signaling inhibitors like ibrutinib (Byrd et al, 2013; Burger et al, 2015) and idelalisib (Furman et al, 2014), and by the prognostic impact of somatic hypermutations and the gene usage of the immunoglobulin itself (Zenz et al, 2010; Duhren‐von Minden et al, 2012).