Properties of STAT3-binding sites genome-wide. (A) Western blot showing phosphorylation of STAT3 in response to IL-10 stimulation. PEC macrophages were treated with IL-10 for 4 hours and protein was extracted and blotted for total STAT3, phospho-Y705-STAT3 (pSTAT3), and GAPDH as a loading control. There are 2 bands for phospho-STAT3, in agreement with the manufacturer's example blots. (B) STAT3 binds to its own promoter in IL-10–treated macrophages, but not in untreated cells. This is a genomic view of the STAT3 ChIP-seq tag density around the Stat3 gene. (C) De novo motifs recovered by MDmodule from the STAT3 binding sites with a RefSeq gene within 2 kb (left motif), and by HOMER from the entire list of STAT3 binding sites (right motif). (D) The STAT3 motif is usually found close to the STAT3 ChIP-seq peak summit (as defined by MACS). (E) The average phastCons vertebrate conservation score at each base centered at the peak summit of the STAT3-bound sites.