In vivo chromatin immunoprecipitation showing Sp4’s interactions with GABAA receptor subunit promoters in mouse visual cortical nuclear extract. Immunoprecipitation was carried out with anti-Sp4 antibodies (Sp4 lane), anti-nerve growth factor receptor p75 antibody (negative control, NGFR lane), or no antibody (negative control, blank lane). 0.5% of input chromatin (Input DNA lane) served as the control for PCR reaction. The positive control for Sp4 binding was GM3 synthase, whereas β-Actin was the negative control. Sp4 interacted with Gabra1 and Gabra2, but not with Gabra3.