Liu et al. found out that IFN-β could instigate tumor-repopulating cells (TRC) of melanoma into dormancy through an indolamine 2, 3-dioxygenase/kynurenine/aryl hydrocarbon receptor/p27–dependent (IDO/Kyn/AhR/p27-dependent) pathway [40]. Here, IDO1 is linked to melanoma.