Functional annotation of the erythroid transcriptomes. (A) Venn diagram indicating lineage restriction of moderate and abundant probe sets. Primitive erythroid probe set expression is exclusive to the primitive erythroid lineage (yellow), adult definitive-restricted probe set expression includes BM erythroid expression as well as probe sets expressed in both the BM and the fetal definitive erythroid lineage (blue). (B) Functional annotation of shared and lineage-restricted probe sets based on DAVID clustering²²  were further grouped to reduce complexity. Bar length indicates the relative number of probe sets within each column associated with a functional category. Bar color indicates whether the functional category contains probe sets present in all (core) erythroid cells as well as probe sets restricted to one or both lineages (red), only probe sets found in all erythroid cells (purple), or probe sets restricted to specific lineages (blue). Although the probe sets constituting primitive erythroid, definitive erythroid, and core erythroid functional categories are nonoverlapping, specific probe sets may be listed in more than one functional category. Lists of probe sets that constitute each functional category are available in supplemental Table 4.