Dll4/Notch inhibits a MK transcriptional program in human CD34⁺CD41⁻ cells. Analysis by quantitative RT-PCR of the expression levels of various genes in sorted CD34⁺CD41⁻ cells cultured onto control or Dll4Fc-coated plated harvested at days 2, 3, and 5 and in sorted CD41⁺CD42⁺ cells cultured onto control or Dll4-Fc-coated, plated, and harvested at day 11. mRNA expression of each gene was normalized to that of HPRT mRNA and calibrated to the gene:HPRT ratio in HEL cells. For each gene, the relative expression levels in populations grown onto Dll4Fc are expressed as fold induction, compared with the levels (set to 1) detected in populations grown onto control plates. Results were obtained from 4 independent experiments. Sequences of the PCR primers are described in supplemental Table 1.