SERPINB1 and cholangiocarcinoma: In this regard, the transcripts ubiquitin conjugating enzyme E2 C (UBE2C) and serine protease inhibitor B1 (SERPINB1) arose as potential liquid biopsy biomarkers, being increased in urine EVs isolated from patients with CCA in comparison to a group containing patients with PSC, UC and healthy controls (Figure 9A,B).