FGF signals facilitate HSPC expansion through FGFR1. (A) BM Flk2⁻LSK cells from Mx1:Control or Mx1:CKO cultured with or without SU5402 14 days. Representative data from 3 independent experiments. (B) Comparison of fold increase of Flk2⁻LSK cells from Mx1:Control, Mx1:CKO and Mx1:Control plus SU5402 at 1 or 5μM after 14 days culture (n = 6). (C) Comparison of fold increase of CD34⁻LSK cells from BM cells and sorted LSK cells from Scl:Control and Scl:CKO mice, respectively, plus FGF1, 2, 4, or 10 with standard medium after 14 days culture (n = 3). (D) Gene expression analysis of NFκB using qRT-PCR on BM Flk2⁻LSK cells from Mx1:Control, Mx1:CKO mice on the days indicated after 5FU (n = 3). (E) Representative immunostaining and quantification of subcellular location of NFκB in CD34⁻LSK cells sorted from Scl:Control and Scl:CKO mice. Data pooled from 2 independent experiments. (F) Comparison of fold increase of CD34⁻LSK cells from BM cells in C57Bl/6 WT mice plus FGF1, FGF2, or with standard medium plus NFκB inhibitor at 1 or 5μM, respectively, as indicated after 14 days culture (n = 4).