CD274 and cancer: Chemoresistance due to significant upregulation of PD-L1 expressions in cancer cells by various drugs, such as doxorubicin (DOX), Oxaliplatin (OXA, a DNA alkylating agent), Paclitaxel (PACLI, a tubulin inhibitor), Irinotecan (IRI, a topoisomerase 1 inhibitor) has been found and the role of ERK activation increase has been correlated to the overexpression of PD-L1 (14, 39).