Moreover, a variant of the AML1-ETO fusion protein, Runx1-Runx1t19a (ETO9a), which includes an extra exon 9a of the Runx1t1 gene that contains C-terminal truncation, was found to be a much more potent inducer of leukemia than the full-length Runx1-Runx1t1 in mouse retroviral transduction–transplantation model [140]. This evidence concerns the gene RUNX1 and leukemia.