Role of α₄ integrins in the interactions of the FDCP-mix progenitor cell line with the bone marrow microvasculature. Fluorescently labeled FDCP-mix cells preincubated with control rat IgG (□), anti-α₄β₇ integrin antibody (clone DATK32; ▦), or anti-α₄ integrins (clone PS/2; ▪) were injected into lethally irradiated E-selectin–deficient mice. The fractions of cells rolling or arrested on the BM microvasculature were determined by analysis of video recordings from fluorescence intravital microscopy experiments. n = 6 mice; *P < .05; **P < .01 compared with the rat IgG control group or between indicated 2 groups. Data are presented as means ± SEM.