Anti-tumor effects of NK cells and anti-PD-L1 antibody with antibody-dependent cellular cytotoxicity in PD-L1-positive cancer cell lines ======================================================================================================================================== * Ji-Eun Park * Seong-Eun Kim * Bhumsuk Keam * Ha-Ram Park * Soyeon Kim * Miso Kim * Tae Min Kim * Junsang Doh * Dong-Wan Kim * Dae Seog Heo