USP20 and gastric cancer: Wang et al. verified that both USP20 and Claspin proteins are expressed at low levels in human gastric cancer tissues, and this phenomenon was also observed in gastric cancer cell lines (MGC-803, NCI-N87, MKN45, BGC-823, KATO III, SGC-7901, AGS, SNU-1, SNU-16 and MKN74) [60].