Compositions, e.g., therapeutic agents, and methods are provided for modulating gene and protein expression of Forkhead Box protein 1 (Foxp1). The therapeutic agents include short nucleic acid molecules that modulate gene and protein expression of Forkhead Box protein 1 (Foxp1) expression, viral vectors containing such molecules, T cells transduced with these viruses for adoptive therapies, and any small molecules that bind to and inactivate Foxp1. These compounds and methods have applications in cancer therapy either alone or in combination with other therapies that stimulate the endogenous immune system in the environment of the cancer, e.g., tumor.