LacZ, coding for the enzyme ß-galactosidase (Gal), was not only a marker to visualize individual tumor cells but it also served as a surrogate tumor-associated antigen (TAA) that induced major histocompatibility complex (MHC) class I-lacZ-peptide specific CD8 cytotoxic T lymphocytes (CTL) [4]. The gene discussed is CD8A; the disease is neoplasm.