CD34⁻ LT-HSCs expressing high levels of Notch are sensitive to Lrf inactivation. (A) Histograms show mean fluorescence intensity (MFI) for Notch1 and Notch2 in indicated HSC/progenitor compartments. Signal levels in Notch1-deficient LT-HSCs (N1 KO: Notch1^Flox/FloxMx1-cre⁺) and fluorescence minus one (FMO) controls are also shown. CLP: Lin⁻IL7Rα⁺Flt3⁺CD48⁺; LMPP: Lin⁻IL7Rα⁻Sca1⁺c-Kit⁺Flt3⁺CD150⁻CD48⁺. (B) CD34⁻ LT-HSCs expressing high levels of Notch are lost after Lrf inactivation. Representative FACS profiles for Notch1 and Notch2 in control (Zbtb7a^Flox/FloxMx1-Cre⁻) and Lrf knockout (Zbtb7a^Flox/FloxMx1-Cre⁺) mice. All mice were injected with pIpC 3 times, and Notch expression levels within the CD34⁻ LT-HSC population analyzed 1 month after the last injection. Data for Notch1 KO, FMO, and control are same as those shown in panel A. (C) Graph shows MFI of Notch staining in control (black) and Lrf-deficient (red) CD34⁻ LT-HSCs 1 month after the last injection. Error bars: standard deviation.