Anti–integrin α6 or α4 antibodies do not affect HSC survival or engraftment. CD45.1 BM cells were incubated with rat IgG isotype control antibody (rIgG), anti–integrin α6 (α6) or α4 (α) antibodies and injected into lethally irradiated CD45.1/2 mice, followed by injection of CD45.2 competitor BM cells 3 hours later. The percentages of CD45.1 nucleated cells and CD45.1 myeloid cells in blood at 3, 6, and 16 weeks after transplantation are shown. The horizontal bars indicate mean values.