CD1D and neoplasm: Importantly, stimulation with PolyI:C, a dsRNA analogue commonly used for bystander activation of NK cells [53], did not increase killing of RMA and only minimally enhanced RMA-S killing in B6 mice or CD1d−/− but induced elimination of both MHC-I+ and MHC-I− tumor cells in MHC-I−/− mice (Figure 5B–D).