RXRA and neoplasm: Recent reports showed that combination of anti-PD-1/PD-L1 therapy with MEK inhibitor34, BTK inhibitor35, PPARγ/RXRα inhibitor36, TNF superfamily member LIGHT37,38, immunogenic chemotherapy39, photodynamic therapy40,41, and irradiation42,43 would promote T-cell infiltration and anti-tumor activity of checkpoint inhibitors.