CD4 and cancer: CD73 expression was found in both tumor area staining up to 100% of cancer cells (figure 2A) and in the tumor stroma (figure 2C) staining CD4+ and CD8+ T cell, as well as other (non-CD4 non-CD8) cells (figure 2D,E), which is in line with our flow cytometry data showing that the source of CD73 can come from multiple different cell types including immune cells, EPCAM+ cells and fibroblasts (figure 1C).