The finding that the major histocompatibility complex (MHC) class II t
rans-activator (CIITA) gene product plays a role in the regulation of
transcription of MHC class I genes suggests a common regulation of tra
nscription of class I and class II genes. Here, Peter van den Elsen an
d colleagues argue that the RFX complex also plays a role in the regul
ation of transcription of class I genes.