CTLA4 and neoplasm: For delivery of anti-CTLA4 immunotherapy, we used three different approaches; i) systemic application of a monoclonal antibody against murine CTLA4 (4F10), ii) intratumoral expression of a secreted form of this antibody from genetically modified tumor cells, iii) expression of the anti-CTLA4 antibody after gene delivery using a stem cell based approach.