Fig. 3

Transcription factors GATA-1 and SP1 in differentiating fetal erythroid cells

The free probe and the shifted bands are indicated by the arrows. The day of harvest and EPO addition are shown above. The lanes are numbered below. (a) GATA-1 binding activity. (b) SP1 binding activity. Lanes 1 and 2, nuclear extracts of K562 cells as a positive control; Lanes 2 and 13 (designated c), cold competition—binding in the presence of 100-fold molar excess of unlabeled oligonucleotide; Lanes 3–13, fetal liver cultures, first and second phase; Lanes 14 and 15, binding activity of nuclear extracts of a normal adult-derived culture grown, harvested and analyzed in parallel to the fetal liver culture; Lanes 16–19, nuclear extracts of a parallel culture of the same liver, grown in the second phase in the absence of EPO. (c) Quantification of the autoradiograms (shown in a and b). (d) GATA-1 and SP1 binding activities of a normal adult-derived culture. ●, GATA-1 binding activity; ○, SP1 binding activity.