Electroporation experiments with the t(4;11)-positive AML and ALL cell lines MV4-11 and SEM, respectively, showed that siRE-mod did not affect proliferation of either cell line while siRNAs targeting MLL/AF4 inhibited proliferation and colony formation of SEM cells (Supplementary Fig. 1g–i). The gene discussed is AFF1; the disease is acute myeloid leukemia.