CD9 and acute myeloid leukemia: As shown in Figure 3, to devise the Urayasu classification for AML based on the expression patterns of important treatment resistance factors, in addition to the status of expressions of p53 and MRP1, we proposed the addition of the status of expressions of AKR1B10, an enzyme that degrades idarubicin, and AKR1B1, a competitive inhibitor of AKR1B10.