CD37 and acute lymphoblastic leukemia: The mRNA level of CD37 was highest in THP-1 (M5), OCI-AML2 (M4), MV4-11 (M5), and HEL (M6) but significantly lower in other AML cell lines (HL-60 and NB4), ALL cell lines (JURKAT, NAML-6, and SUP-B15), and chronic myeloid leukemia (CML) cell line (K562) (Figure 1A).