Figure 1. Gel shift assay to determine DNA-binding activity of NFAT and NFB transcription factors. Nuclear extracts were obtained from human gingival fibroblasts exposed to 10 ng/mL TNF- in the presence or absence of 10 µg/mL cyclosprin A. Five µg of nuclear proteins were incubated with [³²P]ATP-labeled oligonucleotide probes, separated as described in the "METHODS", and visualized by autoradiography. For competition, unlabeled nucleotides were added at 100-fold molar excess. Arrows indicate shifted complexes. A, NFAT; B, NFB.