LIL-Stat is constitutively activated in nuclear extracts of CD34⁺ cells and disappears upon differentiation. CD34⁺ cells were incubated with SCF and M-CSF for 0 (lane 1), 1 (lanes 2-4), and 5 days (lanes 5 and 6) and treated with IL-6 (lane 3) or IL-1β (lane 6). Five micrograms of nuclear extracts were used in band-shift assays with the ³²P-labeled LILRE oligonucleotide. Competition was performed using a 100-fold molar excess of unlabeled LILRE (lane 4). Absence of LIL-Stat binding in IL-6–treated monocytes is depicted in lane 7.