The present invention relates to the use of a protein phosphatase inhibitor selected from an inhibitor of the catalytic subunit of the protein phosphatase 1 (PP1), an inhibitor of GADD34 and an inhibitor of the PP1/GADD34 complex to prepare a pharmaceutical composition to prevent or treat a cancer in a mammal, wherein the pharmaceutical composition is intended for administration in combination with a product used in a treatment of a cancer.