Regulation of Nfil3 binding activity by p53 and IL-6. Nuclear extracts prepared from M1p53ts_val mouse myeloid leukemia cells were studied by EMSA with a ³²P-labeled oligonucleotide probe containing the HLF consensus binding sequence. Levels of the Nfil3 complex are shown in the absence of IL-6 in cells maintained at either 37°C (lanes 1 through 3) or after a shift to 32°C (lanes 4 through 6), allowing p53 to assume a wild-type conformation. The effects of IL-6 addition on Nfil3 binding activity are shown at both 32°C (lanes 7 through 9) and 37°C (lanes 10 and 11).