Fig. 2. Gel retardation of GCR and Car3 oligonucleotides by p50 and Dictyostelium cell extracts. Gel shift assays performed with [³²P] labelled GCR, Car3 and Ig oligonucleotides in the presence of 100 ng of recombinant mouse p50 (row 1), 16-hour-developed Dictyostelium nuclear extracts (row 2) and cytoplasmic extracts (row 3). The experiments were performed in the absence (Fig. 2A) or in the presence (Fig. 2B) of a 25-fold excess of non-labelled GCR, Car3 or Ig oligonucleotides used as competitors (italics). Gel shifts were performed as described previously (Traincard et al., 1999), except for experiments performed with Ig as labelled probe in which threefold the amount of Dictyostelium extract was used. n.d., not done.