MAdCAM-1 is expressed in the bone marrow and mediates progenitor homing. (A) RT-PCR analysis of MAdCAM-1 mRNA expression in Peyer patch (PP) and bone marrow (BM) from a wild-type mouse. (B) Lethally irradiated E-selectin–deficient mice (E^–/–) were injected with wild-type (WT) donor BM cells along with anti–MAdCAM-1 (MECA367) and/or anti–VCAM-1 (MK/2) antibodies. Three hours after injection, CFU-Cs were determined from the BM. **P < .01 compared with rat IgG control group, n = 5-11 per group. Data are presented as means ± SEM.