Cooperation of Epo, SCF, and Dex in the regulation of the erythroid gene expression program. Erythroid progenitors were factor deprived and restimulated with Epo, Dex, SCF, Epo/SCF, Epo/SCF/Dex, or Epo/SCF/ZK. Cy5-labeled cDNA synthesized from mRNA of restimulated cells was hybridized in parallel with Cy3-labeled cDNA synthesized from factor-deprived cells to the hematopoietic and the 17K EST arrays. (A) Hierarchic clustering (obtained with the use of Pearson correlation function) of 1200 clones that showed an alteration in gene expression greater than 1.75-fold up- or down-regulation for Epo or SCF, or greater than 1.5-fold up- or down-regulation for Dex. The color scale representing –fold up-regulation (red) or down-regulation (blue) of gene expression is shown on the left. (B) Bar graphs of clones selected for up- or down-regulation by Epo, Dex, or SCF showing the gene regulation by all other factor combinations versus factor deprivation. Fold changes are indicated on the vertical axes as 2log values. Left column shows down-regulated genes; right column, up-regulated genes. The numbers of preselected, regulated genes/ESTs are indicated in the different panels.
