FACS analysis of the lineage-specific surface antigens. Cells of day 14 floating fraction from both wild-type andGATA-1.05 mutant ES cells were analyzed with FACS using three surface antigens as indicated in the figure. Note that, whereas the wild-type floating cells showed 10² to 10³fluorescence intensity range for TER119 antigen, the mutant floating cells did not show such strong intensity. Upper three histograms show results of wild-type cells, while lower three show results ofGATA-1.05 mutant cells.