ACTA1 and cholangiocarcinoma: In line with previous CCA studies,27 whole-section quantification for collagen and activated fibroblast markers within our patient cohort with CCA revealed that resected CCA tumors expressed significantly higher levels of sirius red and alpha-smooth muscle actin (α-SMA) staining compared to normal liver parenchyma, irrespective of CCA subtype (Supplemental Figure S1A–C, http://links.lww.com/HC9/A993, Supplemental Table S4, http://links.lww.com/HC9/A992).