CR2 and CR3 are consistently required for immortalization of myeloid progenitors by MLL-forkhead fusion proteins.

(A) Deletion mutants used for hematopoietic transformation assays are shown schematically on the left. Bar graph (right) indicates the number of colonies generated by the respective constructs in serial replating assays (means ± SDs, n = 3). (B) Western blot analysis demonstrating expression of MLL fusion constructs identified above the respective gel lanes. (C) Phenotypic analysis of cells transduced by MLL-FKHR. Gray histograms represent FACS staining obtained with antibodies specific for the indicated cell surface antigens. Black lines represent staining obtained with isotype control antibodies.