CTLA4 and neoplasm: As shown in Figure 2A, CTLA-4 expression was significantly different in primary CRC, non-tumoral samples, recurrent tumors, and metastatic tumors (N = 736; metastatic = 1 sample, recurrent tumor = 2 samples, primary tumor = 632 samples, and solid tissue normal = 101 samples, p = 2.1 × 10−7).