In order to determine whether CD40L costimulation is effective against a foreign tumor antigen, human papillomavirus type 16 (HPV-16) E7 protein, groups of C57BL/6 mice were vaccinated with pcDNA3-CRT-E7 DNA or pcDNA3-CRT-E7/pcDNA3-CD40L DNA plasmid via IM injection followed by electroporation two times at a one week interval. This evidence concerns the gene CD40LG and neoplasm.