Up-regulation of hypoxia-inducible genes in Rb-null fetal liver without changes in macrophage-specific or PU1 target genes. Quantitative real-time PCR using wild-type and Rb-null total E13.5 fetal liver cDNA was used to validate and extend data from differential microarray analysis of gene expression. Values are the mean value obtained from 3 separate data sets for each genotype with the wild-type values normalized to 1.0 and values for Rb null samples expressed relative to wild-type. Error bars represent the standard deviation from the mean for each genotype.