HOXA9 and infection: To further test the possibility that Hoxa10 could directly activate Myb transcription, we transduced 5-FU-treated mouse bone marrow progenitors with Hoxa10-expressing (MSCV-Hoxa10-PGK-puro), Hoxa9-expressing (MSCV-Hoxa9-PGK-puro) or empty virus (MSCV-PGK-puro), and compared the Myb expression levels in the transduced cells at 72hrs after infection following the elimination of non-transduced cells by selection with puromycin at 48hrs.