Interactions on the MS7 element and CD11a/CD18 expression in t(8;21)–containing cells. (A) Determination of the cell surface expression of CD11a and CD49d integrins on AML1/ETO-expressing Kasumi-1 cells, as determined by flow cytometry using the monoclonal antibodies TS1/11 (anti-CD11a), ALC 1/6.3 (anti-CD49d), and T3b (anti-CD3) as control. i, whole population; ii, percentage of marker-positive cells. (B) CD11a/CD18 cell surface expression on cells from the bone marrow aspirate of a t(8;21)⁺ AML-M2 patient. CD11a expression was determined using the TS1/11 monoclonal antibody. Negative control fluorescence was determined using the supernatant from the myeloma P3X63 (X63). (C) DNA affinity precipitation on the MS7 element. COS cells were transfected with expression vectors for either RUNX1 or AML-1/ETO, and cells extracts were incubated with biotinylated MS7 oligonucleotide. DNA-protein complexes were isolated by centrifugation with streptavidin-agarose, and bound proteins separated by SDS-PAGE and subjected to Western blot using RUNX1 (lower panels) or ETO-specific (upper panels) polyclonal antibodies. As a control, cell lysates from transfected and Kasumi-1 cells (left panels) were analyzed in parallel.