Expression of laminin β2 chain in normal human bone marrow and ex vivo–expanded CD34⁺ peripheral blood progenitor cells. (A) Negative control with nonimmune mouse serum. (B) Laminin β2 chain expression as pericellular staining of bone marrow mononuclear cells. (C) Laminin β2 chain expression of normal megakaryocytes (arrow) and as extracellular deposition. (D) Laminin β2 chain expression in hematopoietic cells generated ex vivo from purified CD34⁺ peripheral blood progenitor cells.