Gel mobility shift reaction with 5′ c-junprobe shows two distinct complexes containing c-jun protein. A gel mobility shift assay was performed with nuclear extracts (10 μg) from Bcr-Abl.A54 cells. Cold-competition with nonradioactive self probe (100×) or with nonradioactive commercial oligonucleotide containing a 7-base TRE was accomplished. Specific supershifting of the band-shift complexes (a, b) was shown with c-jun antibody, but not by Sp1 or jun B antibodies.