Strikingly, immunofluorescence staining of tumor sections showed an increase in the number of CD8+T cells in the papaverine-treated tumor compared to the vehicle-treated control tumor; GLUT1 staining, a HIF1 and hypoxia marker, further supported decreases in hypoxic regions in the papaverine-treated group (Fig. 1F,G). Here, SLC2A1 is linked to neoplasm.