NOTCH4 and gastric cancer: Of those 22 proteins, the following 9 were upregulated in GC tissues [1]: proliferating cell nuclear antigen (PCNA), Notch4, cyclin-dependent kinase (CDK)4, CDK6, X-linked inhibitor of apoptosis protein (XIAP), p-protein kinase C (PKC)α/βII, Akt, β-catenin, and p-PKCα.