IGFBP2 supports the survival and cycling of HSCs in the BM. (A) Lin⁻Sca-1⁺Kit⁺ cells from BM of WT or IGFBP2-null mice were analyzed for early apoptosis (annexinV⁺7-AAD⁻) and late apoptosis (annexinV⁺7-AAD⁺) markers (n = 6). (B) Cell cycle status of Lin⁻Sca-1⁺Kit⁺Flk2⁺CD34⁺ cells and (C) Lin⁻Sca-1⁺Kit⁺Flk2⁻CD34⁻ cells was evaluated by Hoechst 33 342 and pyronin Y staining (n = 6). (D) BrdU incorporation into Lin⁻Sca-1⁺Kit⁺ cells was measured (n = 8). (E) The expression of certain growth and survival related genes in freshly isolated BM Lin⁻Sca-1⁺Kit⁺ cells was evaluated by real-time RT-PCR (n = 4-6).