Increased cell proliferation in patients with aGVHD. (A) Representative MIB-1 immunohistochemical staining of the initial gut biopsies of a control (left) and an aGVHD patient (right). Shown magnification is ×20. (B) Immunohistochemical scoring of the MIB-1 staining shows a significant increase of proliferating enterocytes in aGVHD patients compared with controls.