Northern blot analysis of AML1-ETO expression in the bone marrow or bone marrow colonies of founder line #8.

Transgenic mice that were positive for either MMTV-tTA or for MMTV-tTA and pUHD–AML1-ETO were killed, and bone marrow was harvested from the femurs and tibias of these mice. Some of the bone marrow from these mice was used to perform CFU assays. Total RNA was harvested from the rest of the bone marrow from the double-positive mice as well as from the colonies from the CFU assays. Each RNA sample (10 μg) was electrophoresed. The RNA was then transferred to a nylon membrane and hybridized with a fragment of the ETO cDNA. The ethidium bromide staining of the 18S ribosomal RNA is presented to show the loading of the RNA samples.