Nucleofected DCs induce strong primary and memory antitumor immunity. (A) When tumor cells and DC vaccination are given at the same time, mice vaccinated with DCs encoding GFP-OVA fusion protein (pGO) are protected against tumor cells, whereas mice vaccinated with DCs encoding for GFP alone (pG) are not. The protective primary response was not affected even if the CD4 T cells were depleted before DC vaccination (pGO CD4 dep). (B) When memory response against tumor cells was measured by vaccinating the mice 3 weeks before tumor challenge, mice vaccinated using DCs nucleofected with pGO were almost completely protected against the tumor cells, whereas CD4 T-cell depletion abrogated the protection. P values were calculated using the Student t test.