Integrin expression and hematopoiesis in β₁^Δ/Δ at steady state. (A) Expression of various integrins in CD45⁺ BM cells of β₁-deficient (β₁Δ, thick black line) or β₁-sufficient, control (β₁⁺, gray histogram) mice; isotype-matched control is represented by a thin dotted line. Note that the expression of α₄β₇ is up-regulated in β₁^Δ/Δ BM cells. (B) Lin⁻, Sca-1⁺, c-kit⁺ (LSK) cells in the femurs of control (n = 10) and β₁^Δ/Δ (n = 15) mice. (C) Cells and progenitors per femur, spleen, and 1 mL of PB in β₁^Δ/Δ (BM, n = 19; spleen, n = 13; PB, n = 17) or control, β₁⁺ (BM, n = 18; spleen, n = 6; PB, n = 17) mice. White bars represent control mice; and gray bars, β₁^Δ/Δ mice. *Significant difference over control (P < .05). (D) α4 versus α5 expression in β₁^Δ/Δ spleen cells compared with α4^Δ/Δ mice or control mice. (E) Relative expression of α4 and α5 integrin in erythroid cells (TER119⁺) at progressive maturation stages: R1, CD71^hi/TER119^lo (gray shaded area); R2, CD71^hi/TER119^hi (white area with bold line); and R3, CD71^lo/TER119^hi (white area with thin, dotted line). Note the higher α5 expression in early R1 erythroblasts (gray).