STUB1 and gastrointestinal stromal tumor: Furthermore, there was co-localization of STUB1 and GPX4 in the cytoplasm of both GIST-T1 (Pearson correlation coefficient = 0.728 ± 0.024) and GIST-882 cells (Pearson correlation coefficient = 0.689 ± 0.013; Figs. 4A and S4).