Many genes are regulated by IFNγ in Stat1−/−
macrophages. Biotin-labeled cRNA samples were prepared from
Stat1−/− and WT BMM, unstimulated or stimulated for 60
min with IFNγ (14 ng/ml). After hybridization to an Affymetrix
oligonucleotide array complimentary to more than 11,000 mouse genes and
Expressed Sequence Tags (ESTs), and staining and scanning of the
arrays, the data were analyzed with the Affymetrix software. This
experiment was performed three times [twice with the 6,400 and once
with the 11,000 (11k) GeneChips], using freshly prepared RNA for each
experiment, with similar results. (A) Representation of
the average differences (relative indicator of the level of expression
of a transcript) for the untreated- and IFNγ-treated WT and
Stat1−/− BMM. The plots contain only those genes that
showed an average difference of greater than 100 compared with the
untreated sample. Each graph represents the changes observed for
≈8,500 genes. (B) Comparison of IFNγ-dependent gene
regulation in WT and Stat1−/− BMM, assessed by using the
sort score, a parameter based on a combination of the relative change
in mRNA expression levels and the intensity differences shown for a
specific gene after IFNγ stimulation.