To test the function of lin28Tg CTLs in anti-tumor responses, B16F10 mouse melanoma cells were genetically engineered to co-express a GFP reporter and the gp33-41 peptide (Supplementary Fig. 1a, referred to as B16gp33) from the lymphocytic choriomeningitis virus (LCMV), such that tumor-specific lysis can be assessed using P14 T cell receptor transgenic CD8 T cells which recognize the gp33-41 peptide in the context of the Db molecule27. Here, CD8A is linked to neoplasm.