NPM1 and acute myeloid leukemia: When we performed substratification of AML-NK patients based on the presence of FLT3-ITD and NPM1 mutations into 3 risk groups (favorable NPM1+-11 patients, poor FLT3-ITD+-12 patients, and intermediate FLT3-ITD−/NPM1− −28 patients), we have found that ABCB1+ status was predominant in the FLT3-ITD−/NPM1− group, because 71% of FLT3-ITD−/NPM1− patients had high ABCB1 expression (P = 0.001).