Fig 3. Identification of transcription factors binding to the Sp1 sequences within the -660/-233 fragment of the hFCGRT promoter.

Supershift experiments were performed by preincubating the nuclear extract from differentiated THP-1 cells on ice for 1 h with 2 μg of rabbit polyclonal antibodies specific for the Sp family transcription factors or normal rabbit IgG prior to the addition of ³²P-labeled wild-type probes: Sp1-1+2(WT), (A); Sp1-3(WT), (B). Labeled probe alone (A and B, lanes 1); labeled probe incubated with nuclear extract in the absence of antibodies (A and B, lanes 2); in the presence of rabbit polyclonal antibodies: anti-Sp1 (A and B, lanes 4), anti-Sp2 (A and B, lanes 5), anti-Sp3 (A and B, lanes 6), anti-AP-2 (A, lane 7), normal rabbit IgG (A and B, lanes 3). Shifted bands are imarked with an asterisk. Results were analyzed by a phosphor imager.