Generation of Mll and Mll/Hox mice. PCR results on mouse tail DNA showing wild-type, heterozygous, and homozygous Hoxa9 knock-out mice (left panel). Neo indicates neomycin-resistance gene. PCR for Mll-AF9 is shown on the right panel with the genotypes as indicated. TSH indicates β subunit of thyroidstimulating hormone used as an internal control for the PCR reaction.