INS and influenza: To test whether NKp46 interacts with insulin we incubated the BW-NKp46 cells with purified insulin, BSA or glucagon in the presence or absence of the tumor cell line 721.221 that express an unknown ligand for NKp46 [7], or with 721.221 cells infected with influenza and expressing as a result hemagglutinin, a known ligand for NKp46 [7].