MS4A1 and B-cell chronic lymphocytic leukemia: Furthermore, FMC7 and CD43 are also characterized by differential expression among the three immunophenotypic types of MBL; more specifically, FMC7 exhibits low expression levels in ‘CLL-like’ MBL, intermediate levels in atypical, and high levels in the ‘CD5-negative’ type of MBL, while the exact opposite pattern is evident for CD43 expression (6).