Hoxb4 is down-regulated in the fetal liver. Flow cytometric analysis of FL cells from WT and Hoxb4^YFP/+ embryos at E12.5 and E14.5. (A) Gating of the LSK population is shown by 4 gates representing the major populations, marked R1 to R4. (B) Comparison of gated populations R1 to R4 indicated in panel A showing YFP expression at E12.5. In the histograms dashed lines indicate WT and solid lines indicate Hoxb4^YFP/+ cells. (C) Labeling is identical to panel B but at E14.5. The fold change in mean fluorescence intensity between WT and Hoxb4^YFP/+ at E12.5 is 2.39 (SD = 0.35) and at E14.5 is 1.48 (SD = 0.087); P = .02. Data are representative of 3 independent experiments.