CNTN2 and neoplasm: Sheep S2531 was injected with PBMCs isolated from S19, a sheep that had been inoculated in a previous study with YR2LTaxSN, a BLV-infected tumor B-cell line carrying both a silent TaxK303-mutated transactivation-deficient BLV provirus and a MoMuLV-derived retroviral vector expressing a functional Tax protein [8].