On page 583 in the 4 February 2016 issue, a reference citation is missing in the last sentence of the “Cells and reagents” section of “Materials and methods.” The sentence should read, “Methods for induction of CLL cell proliferation69 and drugs used are detailed in the supplemental Materials and Methods and supplemental Figure 2.” The corresponding reference is shown below. The error has been corrected in the online version, which now differs from the print version.

69. Pascutti MF, Jak M, Tromp JM, et al. IL-21 and CD40L signals from autologous T cells can induce antigen-independent proliferation of CLL cells. Blood. 2013;122(17):3010-3019.