CD4 and malignant glioma: Despite a transient increase in mRNA, type I IFNs did not enhance SAMHD1 protein expression in human primary dendritic cells, macrophages, or CD4+ T cells, but type I IFNs induced SAMHD1 expression in cell lines such as HEK 293T, HeLa, and U87 malignant glioma [34,35].