For in vivo experiments performed with C57BL/6 mice (as depicted in Figure 5D), compared to WT cells treated by TPS, WT cells treated by TPA showed fast tumor growth, evident IDO1 expression, reduced relative Trp concentration, an increased relative [Kyn]/[Trp] ratio, and decreased CD8+T proportion in TIL (panel D). Here, IDO1 is linked to neoplasm.