Moreover, time-course experiments with a Cas9-GFP protein transfected in human CLL cells showed complete disappearance of the signal after 72 h coculture on 3T3-CD40L fibroblasts, further suggesting that the observed increase of NFKBIE MAF in cells stimulated with CD40L or CpG was because of positive selection of cells with such mutations (Fig. 3C). Here, CD40LG is linked to B-cell chronic lymphocytic leukemia.