MLLT3 and acute monocytic leukemia: To corroborate these findings, we used retroviruses expressing MLL fusions which are frequently found in acute monoblastic leukemia (AML M5) and are associated with an unfavorable prognosis in AML, namely MLL-ENL (fusion oncogene resulting from t[11;19]) and MLL-AF9 (resulting from t[9;11]; Krivtsov and Armstrong, 2007; Lavallée et al., 2015).