Absence of laminin β2 polypeptide in the bone marrow. (a); immunoblotting of proteins from 4-weeks-old rat bone marrow (BM) and newborn rat kidney with the MoAb, D5, shows a band of about 190 kD corresponding to laminin β2 in kidney lysates but not in bone marrow. Position of 200 and 97 kD molecular mass markers run in parallel are shown on the left. Immunofluorescent staining with the antibody D5 does not stain any structures in newborn rat bone marrow (b), whereas the antibody stains an artery in the dermis in the same section (c).