Erratum An Mll-Dependent Hox Program Drives Hematopoietic Progenitor Expansion Patricia Ernst, Meghann Mabon, Alan J. Davidson, Leonard I. Zon, and Stanley J. Korsmeyer The authors would like to correct a labeling error referring to data presented in Figure 3D of this paper (Curr. Biol. 14, 2063–2069). The graph labeled Hoxb3 actually represents Hoxb1 transcript. The text also incorrectly refers to this data as representing Hoxb3. The primer sequences listed in Figure S4 are correct, but they are also incorrectly labeled as Hoxb3 primers and probe because they represent Hoxb1 primers and probe. We regret this error and hope that it has not caused any inconvenience.