The group of Ostrand-Rosenberg induced MHC class II expression in tumor cells by transfecting isolated MHC alpha- and beta chain-encoding genes (28, 30), whereas our group has privileged the transfection of tumor cells with the MHC class II transcriptional activator (CIITA), which is the physiological regulator of expression of all MHC class II genes (31–33). This evidence concerns the gene CIITA and neoplasm.