GSEA stratified by distance between-binding site and TSS. Expression array data from MCF-7 cells, incubated for 16 hours in 1% ambient oxygen and treated either with control siRNA or siRNAs directed against both HIF-α subunits,¹⁵  were normalized, filtered for present/absent calls, and ranked according to the fold regulation by HIF-α. High-stringency HIF-1-binding gene loci were stratified according to the distance to the nearest TSS into 4 subgroups. GSEA was performed for each subgroup of genes (www.broadinstitute.org/gsea).^37,39  The cumulative ESs, together with the position of the HIF-binding gene loci among the genes ranked by fold regulation, are plotted for (A) gene loci with the closest HIF-1 binding within 1 kb of the TSS, (B) between 1 kb and 10 kb of the TSS, (C) between 10 kb and 100 kb of the TSS, and (D) greater than 100 kb from the TSS. (E) The log₂ fold regulation by HIF-α is illustrated.