CD4 and neoplasm: The purpose of this study was to expand the understanding of the functional activity of peptide 17.1, as follows: (1) to divide the activity of bifunctional peptide 17.1 to identify its shortened fragments interacting with the TNFR1 receptor or with the Hsp70 protein and (2) to find out the possibility of the binding of this peptide and its shortened fragments with the TNFR1 receptor on the surface of tumor cells and their effect on cytotoxic activity CD4+-T lymphocytes.