ACE2 and pancreatic adenocarcinoma: Similarly, PARD and PAAD were classified as immunologically “cold” with low immune cell infiltration 41, 42, which may contribute to the low cancerous ACE2 expression (Fig. 3h and Fig. S3h) 18; however, we found no significant difference in ACE2 expression between PAAD and adjacent normal pancreas (Fig. 3d and Fig. S3d), the discrepancy may be attributable to the small sample size of adjacent normal pancreas in our study (n = 4).