Two protected regions corresponding to the Sp1 sites were detected by DNA-footprinting analysis. The ability of nuclear proteins to bind and protect the core promoter fragment of the α₂ integrin core promoter was assessed. DNase 1 digestion for 30 seconds and 1 minute of the ³²P-end–labeled DNA fragment (bp −92 to +109) was performed with no nuclear extract and in the presence of nuclear extracts from uninduced and induced K562 cells (at 70 μg) for 30 seconds and 1 minute. The digested products were analyzed on a denaturing SDS-polyacrylamide gel. Sequence reaction of the DNA region was run in parallel and the sequence of the region is shown.