ID2 and neoplasm: Indeed, in a prophylactic tumor vaccination model (Fig 2A) we observed that CTLA-4 blockade started on day 5 after Id2-kd N2a cell implantation resulted in 100% tumor rejection (Fig 2D) in contrast to 80% when given on the same day as the Id2-kd N2a cells (Fig 2C and 2D) highlighting the synergy between immune priming and immune modulation that is required for effective tumor vaccine therapy.