NFKB1 and mantle cell lymphoma: In the bone marrow, another common site of MCL involvement, stromal cells upregulate expression of focal adhesion kinase (FAK), CXCR4 and CXCR5 chemokine receptors, and VLA-4 adhesion molecules, likely resulting in downstream activation of the NF-kB and PI3K/AKT pathways (30, 31).