CD40 and B-cell chronic lymphocytic leukemia: Although MEC1 cells inherently express high baseline levels of various CLL markers (which can vary in expression among patient samples), we detected significant changes in marker expression in recirculating cells, including B cell receptor (BCR) isoforms immunoglobulin D (IgD) and IgM68; cell adhesion, activation, migration, and retention markers such as as CD23,69 CD62L,70 CD69,71 VLA-4 (CD49d/CD29),72 CD44,73 CD38,74 CD40, and CD8075 and homing chemokine receptors CXCR476 and CCR777 (Figures 7B, 7C, and S2; Table S1).