YY1 and neoplasm: Furthermore, Touboul and Bonavida [98] speculated that targeting YY1 may be both inhibiting PD-1 expression on CD8+ CTLs and restoring their anti-tumor activities, and on the other hand, targeting YY1 may be inhibiting PD-L1 on tumor cells, as well as inhibiting tumor cell survival, metastasis, and resistance.