CD38 and B-cell chronic lymphocytic leukemia: We first compared the % Ki-67+ CLL cells between the groups and found that Ki-67 expression in CLL cells (identified by their CD5, CD19 expression) was significantly higher in the VLA-4+CD38+ group than in the VLA-4-CD38- group (median Ki-67 expression 4.72% vs 0.65%) (Fig. 6A).