“In unspecified mesoderm, … find that RA coordinately upregulates anterior 3′ Hox … from clusters A, B, and C , and downregulates posterior 5′ Hox genes from clusters A–D. However, hematopoietic development of mesoderm was inhibited by RA, and we find further that retinoids are entirely dispensable for hematopoiesis in vitro.”