WDFY3 and acute promyelocytic leukemia: In order to test our hypothesis that ALFY is essential for granulocytic differentiation of APL cells, we generated four NB4-derived cell populations stably expressing three different small hairpin RNAs (shRNAs) constructs targeting ALFY (shALFY1–3) and a control shRNA construct (shC), using lentiviral vectors.