The invention relates to the utilization of a peptide for the protection of cells in connection with an in vivo and/or in vitro treatment with chemical agents. Said peptide comprises a modified form and/or optionally a modified fragment of a Bowman-Birk protease inhibitor (BBI). The invention also relates to the utilization of nucleic acid for the protection of cell in connection with an in vivo and/or in vitro treatment with chemical agents, wherein the nucleic acid comprises a sequence segment coding for the at least one peptide mentioned above.