CircUBAP2 (hsa_circ_0007367) was shown to repress antigen presentation and induce immune escape in pancreatic adenocarcinoma (PAAD) through sponging miR-494 to upregulate CXCR4 and ZEB1 proteins, then leading to increased expression of CTLA-4 and PD-1 [292]. Here, CTLA4 is linked to pancreatic adenocarcinoma.