Expression of ZMYM2/FGFR1, BCR/FGFR1, or BCR/ABL1 in human CD34⁺ CB cells leads to expansion of erythroid colonies and induces similar but distinct gene-expression profiles. (A) Cells expressing ZMYM2/FGFR1, BCR/FGFR1, or BCR/ABL1 mainly gave rise to BFU-E colonies after 2 weeks of culture in methylcellulose medium. (B) After replating of colonies, cells expressing a fusion gene almost exclusively formed BFU-E colonies. One representative experiment of 4 is shown. (C) Western blot analysis of STAT phosphorylation after 6 days suspension culture showing that ZMYM2/FGFR1 induced a much lower level of STAT5 phosphorylation than BCR/FGFR1 or BCR/ABL1 (left panel). The right panel shows an independent Western blot analysis, using longer exposure time, in which a weak but distinct band of phosphorylated STAT5 in ZMYM2/FGFR1-expressing cells is observed. Vimentin was used as an endogenous control for equal loading. (D-E) Venn diagrams showing the number of genes that are differentially expressed and commonly regulated in cells expressing ZMYM2/FGFR1, BCR/FGFR1, or BCR/ABL1 compared with MIG control cells. (F) Cells co-expressing ZMYM2/FGFR1, BCR/FGFR1, or BCR/ABL1 and an anti-STAT5 shRNA showed a significant reduction in cell proliferation after 7 days in suspension culture. The data are displayed as the mean cellular expansion for the anti-STAT5 shRNA-expressing cells in percentage of the corresponding control scramble shRNA-expressing cells from 3 separate experiments, with error bars representing SD.