Cdx genes selectively effect the hematopoietic potential and hematopoietic-specific gene expression of CD41⁺c-kit⁺ EB-derived cells. The effect of ectopic Cdx1 and Cdx4 expression on the OP9–colony-forming potential (A) and hematopoietic progenitor activity (B) of CD41⁺c-kit⁺ EB-derived cells was assessed. Data are presented as fold change in colony activity relative to noninduced controls. Error bars represent the standard error. The data represent the average of 4 and 7 independent experiments for iCdx1 and iCdx4, respectively. Ectopic Cdx1 and Cdx4 both enhanced all hematopoietic colony activity when induced during EB differentiation. When induced during secondary assay, Cdx1 suppressed all colony potential. Hematopoietic gene expression in CD41⁺c-kit⁻ and CD41⁺c-kit⁺ cells subjected to ectopic Cdx1 (C) or Cdx4 (D) gene expression was also examined by quantitative real-time RT-PCR. Although Cdx1 induction significantly enhanced the expression of several hematopoietic genes in CD41⁺c-kit⁺ cells, relative to CD41⁺c-kit⁻ cells, Cdx4 induction had only modest effects. Each data point represents the average of between 4 and 6 independent experiments. Error bars represent standard error. P values calculated using nonpaired, 2-tailed Student t test are depicted over bars. Purities were typically more than 90%.