CIITA and chronic myelogenous leukemia, BCR-ABL1 positive: With regard to its functional impact, IFN-γ stimulation resulted in the upregulation of the major histocompatibility complex (MHC)-II and its master regulator class II transactivator (CIITA) in CML stem/progenitor cells, and the enhanced proliferation of the responder CD4+CD69+ T cells [70].