Colony formation of the t(8;21)-negative myeloid leukaemia cell lines MV4-11, NB4, HL60, U937 and K562 was not affected upon electroporation with RUNX1-CBFA2T1 siRNA (data not shown), which argues against a general, unspecific effect of the siRNAs used in this study on leukaemic clonogenicity. The gene discussed is RUNX1T1; the disease is myeloid leukemia.