MEPs isolated from Gata1^low/hGATA1 mice generate few mast cells in BMMC cultures. The gate used to isolate cells with the MEP phenotype (c-Kit⁺CD34⁻) from the marrow of Gata1^low/hGATA1 mice and Gata1^low littermates, as well as from wild-type controls, is presented in the panels on the left, which also include reanalysis for purity (> 95% in all cases) and the levels of mGata1 and hGATA1 gene expressed in the sorted cells (as measured by a specific real-time RT-PCR). The frequency of c-Kit^highFcϵRI⁺ cells in the progeny of MEP purified from the different animals after 6 days of BMMC cultures is presented in the middle panels. The c-Kit^highFcϵRI⁺ cells obtained in the different cultures were purified by sorting (> 95% pure by reanalysis) and analyzed, by real-time RT-PCR, for mGata1 and hGATA1 expression, as well as for expression of mast cell markers, as shown in the right panels. Expression levels are presented as mean ± SD of 2^−ΔCt obtained in three separate experiments per group of mice. Values statistically (P < .01) different from those expressed by wild-type and Gata1^low cells are indicated by single and double asterisks, respectively.