CTLA4 and glioblastoma: Although studies have shown increased infiltration of Treg cells to tumor of glioblastoma patients when compared to healthy controls and an increase in signature gene expression of Treg markers such as Foxp3, CD25, CTLA-4, and GITR by gene-profiling analysis, different laboratories have shown unmatched results on the frequencies of Treg cells by flow cytometry and immunohisto-chemistry [24, 28, 46].