Fli-1 in the hematopoietic HEL cell line binds to GPIX Ets sites. (A) Autoradiogram of a gel supershift experiment. Labeled double-stranded oligonucleotide corresponding to bases -54 to -34 within the GPIX promoter was mixed with nuclear extracts derived from HEL cells followed by addition of the indicated antibody. Shifted complexes are indicated as S1, S2, and S3. Supershifted complexes, observed only in lanes b and c, are indicated as SS1 and SS2. (B and C) Immunoblots of separated extracts from HEL cells (left lanes), K562 cells (center), and 293T cells (right) that were transiently transfected with the CMVFli-1 expression construct. (B) was probed with the anti–Fli-1 (ab 1) antibody used in (A) lane b. (C) was probed with the same anti–-Fli-1 (ab 2) antibody that was used in (A) lane c. Arrows identify bands of reactive protein that correspond to the sizes of the two isoforms of Fli-1. Numbers on right indicate molecular weight markers.