CD28 and gastrointestinal stromal tumor: Apoptosis of colon carcinoma, cells (BCL2), apoptosis of lymphoma cell lines (BCL2, IGFBP4, MAP4K1, PDGFRA), cell-cell contact of endothelial cells (STAB1), lymphocyte quantity (BCL2, CCR7, CD28, ITGB7, ITK, MUC1, WNT4), proliferation of lymphocytes (CD28, ITK), gastrointestinal stromal tumor (PDGFRA), metastasis (CD28, ENPP2, FKBP1A), transmembrane potential of mitochondria (BCL2, CD28, EYA2, LGALS2, MUC1)