Mixed and blast-type hematopoietic colonies derived from wild-type and GATA-2^−/− yolk sac cells at E9.5. Cells collected from the yolk sac at E9.5 were subjected to progenitor assay using medium containing KL, IL-11, IL-3, and Epo. Mixed and blast-type colonies from wild-type (A and C) and GATA-2^−/− (B and D) cells were examined on day 9 in culture. This finding was reproduced in 4 GATA-2^−/− embryos analyzed from 2 litters.