Using 13 paired primary MCL tumors and a whole exome sequencing approach (WES), Chenglin et al. identified 18 recurrently mutated genes, including ATM, MEF2B, and MLL2 and novel mutation targets such as SIPR1 and CARD11. CARD11 is a scaffold protein that acts downstream of BTK signaling and functions by regulating NF-κB signaling. This evidence concerns the gene NFKB1 and mantle cell lymphoma.