Abstract: This invention relates to the preparation of a peptide compound (SYRAPRO-2000), its use to activate protein phosphatase-2A enzymes for the dephosphorylation of proteins in vitro and in the cell and its use for inhibiting cell proliferation and induction of death of brain cancer cells and other cancer cells and therefore the treatment of proliferative disorder such as brain cancer and other forms of cancer. Drugs that target the enzymes of the protein phosphorylation/dephosphorylation apparatus of the cell are mostly inhibitor compounds. The present invention describes for the first time the use of an activating compound of a protein phosphatase to modulate the activity of a cell. In this invention, the peptide compound activator of protein phosphatase-2A1 (SYRAPRO-2000) is used to activate protein phosphatase-2A1, thereby causing inhibition of cell proliferation and induction of cell death of transformed T cells and brain cancer cells.