Expression of CD41, c-kit, MECA32, and CD45 in transcription factor mutant EBs.

(A) D6 EBs from wild-type, SCL^−/−, and runx1/AML1^−/− ES cells were stained for the expression of CD41 and c-kit. In SCL^−/− ES cells, no expression of CD41 can be detected, whereas in runx1/AML^−/− EBs, the CD41⁺ c-kit⁺ population is absent. (B) D6.75 EBs were stained for CD41 and MECA 32. Wild-type EBs demonstrate intermediate/low expression of MECA32 in CD41⁺ cells, whereas CD41⁺ cells in runx1/AML1^−/− EBs fail to down-regulate MECA32. (C) D6 EBs were stained for CD41 and CD45. Wild-type EBs show that CD45⁺ cells form a subpopulation within CD41⁺ cells. Runx1/AML1^−/− EBs fail to express CD45.