GAD1 and cholangiocarcinoma: Among all the 105 transcripts identified, c-Maf inducing protein (CMIP), glutamate decarboxylase 1 (GAD1), nucleoside diphosphate kinase 1 (NME1), CDP-diacylglycerol synthase 1 (CDS1), and cyclin-dependent kinases regulatory subunit 1 (CKS1B) constituted the best liquid biopsy candidate biomarkers, as their levels were increased in serum EVs and presented AUC values of 0.957, 0.928, 0.899, 0.893, and 0.891, respectively, for the diagnosis of CCA in comparison with patients with PSC, UC, and healthy individuals grouped together (Figure 5A–E).