KLK4 and cholangiocarcinoma: As presented in Table 2, the proteases ‘a disintegrin and metalloproteinase with thrombospondin motifs 4′ (ADAMTS4), chymase (CMA1) and kallikrein-4 (KLK4) were predicted based on the bile peptide markers to be significantly increased in CCA compared to benign strictures (p <  0.05).