Pfn1 supports the survival of HSCs. (A) Cultured HSCs were stained with Hoechst 33342 and pyronin Y and analyzed for cell cycle stage. The percentages of G0 cells in cultured control and Sclpfn1 HSCs are shown (n = 3; *P < .05). (B) LT-HSCs (as Lin⁻Sca-1⁺Kit⁺Flk2⁻CD34⁻ cells) were isolated from control and Sclpfn1 mice 4 days after tamoxifen treatment and cultured in STF medium for 8 to 10 days. Figures are representative for samples after a 10-day culture. (C) Quantification of control and Sclpfn1 HSCs after 10 days in culture (n = 3; *P < .05). (D) Cultured HSCs from control and Sclpfn1 mice were analyzed for apoptosis using Annexin V/7-AAD staining (n = 3; *P < .05).