IL-21-mediated reversal of NK cell exhaustion facilitates anti-tumour immunity in MHC class I-deficient tumours oleh Hyungseok Seo, Insu Jeon, Byung-Seok Kim, Myunghwan Park, Eun-Ah Bae, Boyeong Song, Choong-Hyun Koh, Kwang-Soo Shin, Il-Kyu Kim, Kiyoung Choi, Taegwon Oh, Jiyoun Min, Byung Soh Min, Yoon Dae Han, Suk-Jo Kang, Sang Joon Shin, Yeonseok Chung, Chang-Yuil Kang