The following plasmids were previously described: pGa981/6, pcDNA3-Flag-SPOC, pcDNA3-RBP;33 (link) pcDNA3-Flag-SPOC pcDNA3-F3, pcDNA3-F3-AML1-ETO, pcDNA3-AML1-ETO(tr)-GFP;31 (link) pcDNA3-Flag-SPOC (Y3602A), pcDNA3-Flag-SPOC (K3516A), pcDNA3-Flag-SPOC (R3552A/R3554A), pcDNA3-RBP-SPOC pcDNA3-RBP-SPOC (Y3602A), pcDNA3-RBP-SPOC (K3516A), pcDNA3-RBP-SPOC (R3552A/R3554A).34 (link) The plasmid pMYs-IRES-GFP was commercially achieved from Cell Biolabs, San Diego, CA, USA. Sequence information of all additional vectors used in this study is available on request.