On the opposite, an alternatively spliced isoform of the RUNX1-RUNX1T1/AML1-ETO transcript, AML1-ETO9a, which includes an extra exon (9a) of the ETO gene, leads to the rapid development of acute leukemia in a mouse retroviral transduction-transplantation model [42]. This evidence concerns the gene RUNX1T1 and acute leukemia.