Changes in gene and protein expression during the transition of EryPs from the YS to the embryonic circulation. (A) Gene identifiers of EryP progenitors. Transcripts expressed by E8.5 EryPs are grouped into functional categories. The fold change from E8.5 and E9.5 is shown. Positive value, up-regulated; negative value, down-regulated. (B) FACS profiles of CD41 protein expression on ϵ-globin::H2B-EGFP embryos from E7.5-E9.5. Expression increases from E7.5-E8.5 and then declines by E9.5. Expression is undetectable at later stages (not shown). (C) FACS histograms showing down-regulation of adhesion molecules on ϵ-globin::H2B-EGFP EryPs during the transition from the YS stage to the circulation.