Supplementary Figure 15: ERG and ERGalt colony-forming assays.

(a) Schema for colony assays. Mouse Arf^–/– lineage-negative bone marrow was cotransduced with GFP-expressing bi- or tricistronic vectors also expressing NRAS Gly12Asp and/or wild-type ERG or ERGalt together with RFP-expressing empty vector or IK6-expressing vector. Flow-sorted GFP⁺RFP⁺ cells were plated in methylcellulose and lymphoid cytokines (IL-7, FLT3L and SCF), and colonies were counted and scored after 7–10 d, collected and replated. (b) Cells expressing NRAS Gly12Asp or WT ERG result in non-sustained replating in the absence of the dominant-negative form of IKZF1, IK6, but ERGalt results in sustained replating particularly in the presence of NRAS Gly12Asp with or without IK6. Representative colony morphology (showing GFP and RFP positivity) and immunophenotyping data are depicted showing pre-B immunophenotype.