IGFBP2 and acute myeloid leukemia: Although IGFBP2 mRNA was expressed at the highest levels in the M3 subtype NB4 AML cells, it was also highly expressed in some other AML and B cell-derived ALL (B-ALL) cells including MV4-11 (M5 AML), U937 (B-ALL), and RCH-ACV (B-ALL) (Figure 1B).