Apoptosis, proliferation, bax, bcl-2 and p53 status prior to and after preoperative radiochemotherapy for locally advanced rectal cancer - Tannapfel, A; Nüsslein, S; Fietkau, R; Katalinic, A; Köckerling, F; Wittekind, C (Int J Radiat Oncol Biol Phys, 1998)