FURIN and acute myeloid leukemia: Taking advantage of uPA/uPAR overexpression in AML relative to normal tissues [213,221], coupled with the DT-dependency on cell-surface proteolytic activation, DT388GMCSF’s specificity to AML was enhanced by engineering the DT furin site to acquire an AML-selective protease system, such as uPA/uPAR, for PrAg-U2.