Figure 4

Basal expression level predicts hypoxia-inducibility. (a) Genes were divided based on their MAS5 present/absent calls under normoxic conditions (0 h). In both cell types, most genes whose expression was up- (gray) or down-regulated (black) by hypoxia were already expressed under basal conditions (Present). (b) Approximately 60% of all genes are permissive (H3K4 me3+, RNA Pol II+, or MAS5 present) under normal growth conditions (All, normoxia). Most genes for which mRNA levels were significantly up- or down-regulated upon hypoxia were permissive under normoxia. Statistical significance was determined by Fisher exact test, and was P-value <1e-150 for all pairwise comparisons. (c) For both cell types, genes were partitioned as either permissive or non-permissive under normal growth conditions (t = 0 h). Changes in mRNA levels (log2 scale) after 4 h and 12 h of hypoxia treatment are plotted, with non-significant changes (P-value > 0.01) represented as 0.